[Federal Register: June 26, 2003 (Volume 68, Number 123)]
[Rules and Regulations]
[Page 38115-38152]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr26jn03-20]
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Part II
Department of Transportation
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National Highway Traffic Safety Administration
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49 CFR Part 571
Federal Motor Vehicle Safety Standards; Tires; Final Rule
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 571
[Docket No. NHTSA-03-15400]
RIN 2127-AI54
Federal Motor Vehicle Safety Standards; Tires
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation.
ACTION: Final rule.
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SUMMARY: The Transportation Recall Enhancement, Accountability, and
Documentation Act of 2000 mandates that we conduct a rulemaking
proceeding to revise and update our safety performance requirements for
tires. In response, we are establishing new and more stringent tire
performance requirements that will apply to all new tires for use on
light vehicles, i.e., those vehicles with a gross vehicle weight rating
of 10,000 pounds or less, except motorcycles and low speed vehicles.
The final rule increases the stringency of the existing high speed and
endurance tests, defers action on proposals to replace the existing
strength test and the bead unseating resistance test with a road hazard
impact test and a different bead unseating test, respectively, adds a
low pressure performance test, and defers action on a proposal to add
an aging test. Together with new safety information requirements that
we recently established for those tires, the new performance
requirements will improve tire safety.
DATES: This final rule is effective June 1, 2007. Voluntary compliance
is permitted before that date. If you wish to submit a petition for
reconsideration of this rule, your petition must be received by August
11, 2003.
ADDRESSES: Petitions for reconsideration should refer to the docket
number and be submitted to: Administrator, Room 5220, National Highway
Traffic Safety Administration, 400 Seventh Street, SW., Washington, DC
20590.
FOR FURTHER INFORMATION CONTACT: For technical and policy issues: Mr.
George Soodoo or Mr. Joseph Scott, Office of Crash Avoidance Standards,
National Highway Traffic Safety Administration, 400 Seventh Street,
SW., Washington, DC 20590. Telephone: (202) 366-2720. Fax: (202) 366-
4329.
For legal issues: Nancy Bell, Attorney Advisor, Office of the Chief
Counsel, NCC-20, National Highway Traffic Safety Administration, 400
Seventh Street, SW., Washington, DC 20590. Telephone: (202) 366-2992.
Fax: (202) 366-3820.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Executive Summary
A. Highlights of the Notice of Proposed Rulemaking
B. Highlights of the Final Rule
C. Adopted aspects of the NPRM
D. Deferred aspects of the NPRM
II. Background
A. The Transportation Recall Enhancement Accountability and
Documentation Act
B. Safety Problem
1. Outdated Performance Requirements
2. Safety Problems Associated with Tires
C. Existing NHTSA Performance Requirements for Tires
III. Pre-TREAD Enactment Agency Response to Safety Problem
IV. Post-TREAD Enactment Agency Response to Safety Problem
A. Tire Testing and Opening of Docket No. NHTSA-2000-8011
B. March 5, 2002 Notice of Proposed Rulemaking (NPRM)
C. Post-NPRM Technical Submissions to NHTSA Tire Upgrade Docket
1. NHTSA Tire Testing at Standards Testing Labs (STL)
2. Rubber Manufacturer's Association (RMA) Design of Experiment
(DOE) and Confirmation Testing
3. Ford Motor Company (Ford) Tire Aging Analysis
4. Goodyear Endurance Testing
V. Summary of Public Comments on NPRM
A. NHTSA's Proposed Test Procedures
1. High Speed Test
2. Endurance Test
3. Low Inflation Pressure Performance
a. Generally
b. Low Inflation Endurance
c. Low Inflation High Speed
4. Road Hazard Impact
5. Bead Unseating
6. Aging Effects
a. Generally
b. Adhesion (Peel) Test
c. Michelin's Long Term Durability
d. Oven Aging
B. Application of New Standard/Deletion of FMVSS No. 109
C. Modification to FMVSS Nos. 110 and 120
D. Modification to FMVSS Nos. 117 and 129
E. De-rating of P-metric Tires/Tire Selection/Load Reserve
F. Lead Time
G. Shearography Analysis
H. Revise UTQG
I. Additional Questions
1. Opportunity to Harmonize
2. ``Real-world'' Testing Procedures
3. Vehicle Model Year 1975
4. Required Inflation Pressures
J. Other
1. Test Condition Tolerances
2. Tire Pressure Load Reserve Limit
K. Costs
L. Benefits
VI. Agency Decision regarding Final Rule
A. Summary of Final Rule and Rationale
B. Summary of Key Differences between NPRM and Final Rule
C. Performance Requirements
1. High Speed Test
a. Ambient Temperature
b. Load
c. Inflation Pressure
d. Speed
e. Duration
2. Endurance Test
a. Ambient Temperature
b. Load
c. Inflation Pressure
d. Speed
e. Duration
3. Low Inflation Pressure Performance Test
4. Road Hazard Impact
5. Bead Unseating
6. Aging
7. Post-test Pressure Measurement
D. Tire Selection Criteria/De-rating of P-metric Tires
E. Applicability and Effective Dates
F. Other Issues
1. Modification to FMVSS Nos. 110 and 120
2. Modification to FMVSS Nos. 117 and 129
3. Shearography Analysis
4. Revision of UTQG
5. Analysis of Responses to Agency Questions in NPRM
6. Other
VII. Benefits
VIII. Costs
A. Original Equipment Tire and Vehicle Costs
B. Total Annual Costs
C. Testing Costs
IX. Effective Date
X. Rulemaking Analyses and Notices
A. Executive Order 12866 and DOT Regulatory Policies and
Procedures
B. Regulatory Flexibility Act
C. National Environmental Policy Act
D. Executive Order 13132 (Federalism)
E. Unfunded Mandates Act
F. Civil Justice Reform
G. National Technology Transfer and Advancement Act
H. Paperwork Reduction Act
I. Plain Language
XI. Regulatory Text
I. Executive Summary
A. Highlights of the Notice of Proposed Rulemaking
Section 10 of the Transportation Recall Enhancement,
Accountability, and Documentation (TREAD) Act mandates that the agency
issue a final rule revising and updating its tire performance
standards. In response, the agency examined the value of modifying each
of the existing tests in its tire standards applicable to tires for
light vehicles, i.e., those vehicles with a gross vehicle weight rating
of 10,000 pounds or less, except motorcycles and low speed vehicles. In
addition, NHTSA examined the value of adopting several new tests. In
doing so, it placed particular emphasis on improving the
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ability of tires to withstand the effects of factors mentioned during
the consideration and enactment of the TREAD Act, such as tire heat
build up, low inflation, and aging. The agency conducted extensive
testing, data gathering and analyses as well as reviewed other existing
international, industry and national standards and proposals, and
submissions by the public.
As a result of these efforts, the agency identified an array of
amendments for revising and updating its tire standards and thereby
improving tire performance. In the notice of proposed rulemaking (NPRM)
that NHTSA published on March 5, 2002 (67 FR 10050, Docket No. NHTSA-
00-8011), the agency proposed to upgrade its existing requirements and
test procedures addressing the following aspects of tire performance:
Tire dimension, high speed, endurance, road hazard impact, and bead
unseating. The agency proposed also to add new requirements that would
require that underinflated tires and aged tires provide specified
levels of performance.\1\ The agency recognized the potential
significant cost of some of the proposed amendments, but decided that,
in view of the broad mandate in the TREAD Act and the uncertainty
associated with the analysis of benefits and costs, the most
appropriate course of action was for the agency to seek public comment
on the wide array of proposals and use the information in the responses
to adjust and refine the amendments.
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\1\ See 67 FR 69600; November 18, 2002, for the recently adopted
tire information requirements. For the convenience of the reader, we
have placed in the docket for today's final rule a document that
shows how the tire safety information and performance requirements
appear together in Standard No. 139.
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The highlights of the proposal were as follows:
(1) High speed and endurance tests--the current high speed and
endurance tests in FMVSS No. 109, New Pneumatic Tires--Passenger Cars,
49 CFR 571.109, would have been replaced with a more stringent
combination of testing parameters (ambient temperature, load, inflation
pressure, speed, and duration.) The proposed high speed test would have
specified test speeds (140, 150 and 160 km/h (87, 93, and 99 mph)) that
are substantially higher than those currently specified in FMVSS No.
109 (120, 128, 136 km/h (75, 80, 85 mph)). The proposed endurance test
would have specified a test speed 50 percent greater (120 km/h (75
mph)) than that currently specified in FMVSS No. 109 (80 km/h (50
mph)), as well as a duration that is 6 hours longer (40 hours total)
than that currently specified in FMVSS No. 109 (34 hours total).\2\
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\2\ At the specified test speed (120 km/h), the proposed
endurance test distance (4800 km) would have been almost double the
distance accumulated than under the current endurance test (2720 km
at 80 km/h).
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(2) Road hazard impact test and bead unseating test--these two
tests would have been modeled on SAE Recommended Practice J1981, Road
Hazard Impact Test for Wheel and Tire Assemblies (Passenger Car, Light
Truck, and Multipurpose Vehicles), and the Toyota air loss test,
respectively. These new tests would have replaced the strength and bead
unseating resistance tests in the current FMVSS No. 109 with tests that
were believed to be more real-world and more stringent.
(3) Low inflation pressure performance--two alternative tests were
proposed. Both tests would have utilized tires significantly under-
inflated, for instance, 140 kPa (20 psi) for P-metric tires (the low
inflation pressure threshold requirement for warning lamp activation in
the then proposed Tire Pressure Monitoring System (TPMS) standard,
Docket No. NHTSA-00-8572 (66 FR 38982, July 26, 2001)), as the
``inflation pressure'' testing parameter for standard load P-metric
tires.
(4) Aging effects--three alternative tests were proposed that would
have evaluated a tire's long term durability through methods different
than and/or beyond those required by both the current and the proposed
endurance test parameters. The three tests would have used peel
strength testing, long-term durability endurance requirements, and oven
aging, respectively.
(5) Tire Selection Criteria/De-Rating of P-metric Tires--the agency
proposed retaining the de-rating percentage of 1.10 for P-metric tires
used on non-passenger car vehicles and revising FMVSS No. 110 to
specify that the determination of vehicle normal load (``reserve
load'') on the tire be based on 85% of the load at vehicle placard
pressure.
Also, the agency discussed revising FMVSS No. 110, Tire selection
and rims, for passenger cars, 49 CFR 571.110, and FMVSS No. 120, Tire
selection and rims for motor vehicles other than passenger cars, 49 CFR
571.120, to reflect the applicability of the proposed new light vehicle
tire standard to vehicles up to 10,000 pounds GVWR. It also discussed
revising FMVSS No. 117, Retreaded pneumatic tires, 49 CFR 571.117, and
FMVSS No. 129, New non-pneumatic tires for passenger cars, 49 CFR
571.129, to replace the performance tests that reference or mirror
those in FMVSS No. 109 with those specified in the proposed new light
vehicle tire standard.
The agency proposed two alternative implementation schedules for
tires: A two-year phase-in under which all applicable tires would have
been required to comply with the final rule by September 1, 2004, and a
three-year phase-in under which all applicable tires would have been
required to comply with the final rule by September 1, 2005. For light
vehicles, the agency proposed that all those manufactured on or after
September 1, 2004 would have had to comply with the final rule.
The aforementioned proposals are summarized more fully in section
IV.B. of this document.
B. Highlights of the Final Rule
In response to the NPRM, the agency received cost data from
commenters and other information that assisted it in refining its
assessment of benefits and costs and in choosing amendments to fashion
a final rule that will offer the American public enhanced tire safety
and be consistent with the principles of Executive Order 12866. The
resulting final rule establishes new and more stringent tire
performance requirements that apply to all new radial tires for use on
passenger cars, multipurpose passenger vehicles, trucks, buses and
trailers that have a gross vehicle weight rating (GVWR) of 4,536 kg
(10,000 pounds) or less and that are manufactured after 1975, and to
all new passenger cars, multipurpose passenger vehicles, trucks, buses
and trailers that have a GVWR of 4,536 kg (10,000 pounds) or less. The
requirements are fully summarized in section VI.A. of this document.
The agency believes the final rule is a reasoned one that is based
on the best currently available information and that will improve tire
safety. NHTSA believes that this rule will be effective at ensuring
that future tires will have their strength, endurance, and heat
resistance evaluated in a way that will increase the required level of
performance.\3\ As a result, these tires are expected to exhibit less
variability in levels of performance and experience fewer blowouts and
tire failures. Additionally, the reserve load requirements of FMVSS No.
110, combined with the de-rating of P-metric tires when used on SUVs,
vans, trailers, and pick-up trucks, will provide a
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sufficient safety margin for tires used on light vehicles.
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\3\ The agency estimates that 5-11% of tires will have to be
modified to meet this final rule.
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In response to comments from the tire and vehicle industries
arguing that the compliance costs were underestimated in the NPRM and
in recognition of the limited quantifiable safety benefits, NHTSA has
reduced the stringency of some of its proposals and deferred others, to
ensure that this rule's safety improvements will be reasonably related
to the rule's costs.
C. Adopted Aspects of the NPRM
High speed and endurance--The agency is upgrading the existing high
speed and endurance tests, although to a more modest degree than we
proposed. Both the high speed test and the endurance test contain
testing parameters (ambient temperature, load, inflation pressure,
speed, and duration) that make the tests more stringent than those
tests currently found in our tire standards, as well as the tests
suggested by industry. Most significantly, the high speed test
specifies test speeds of 140, 150, and 160 km/h substantially higher
than those specified in the passenger car tire standard. Likewise, the
endurance test specifies a test speed 50% higher than that currently
specified in the car tire standard. Under the new endurance test, a
tire is assessed over 50% more distance than a tire must endure under
the current endurance test.
Low inflation pressure performance--The agency is adopting a low
inflation pressure test that seeks to ensure a minimum level of
performance safety in tires when they are underinflated to 140 kPa (20
psi). That is the minimum level of inflation at which tire pressure
monitoring system warnings will be required to be activated. This
requirement mirrors conditions of long distance family travel and will
assist in ensuring that tires will withstand conditions of severe
underinflation during highway travel in fully loaded conditions.
Applicability and LTVs--Given the increasing consumer preference
for using light trucks for personal transportation purposes, NHTSA is,
for the first time, requiring light trucks to have a specified tire
reserve, the same as for passenger cars, under normal loading
conditions. The agency is also extending the tire performance
requirements for passenger car tires to LT tires (load range C, D, and
E) used on light trucks.
D. Deferred Aspects of the NPRM
Road hazard impact--Instead of replacing the current strength test
with the proposed road hazard test, the agency is retaining the
strength test for passenger car and LT tires. Post-NPRM agency testing
data and public comments called into question whether the proposed road
hazard impact test, which was modeled after a SAE recommended practice,
would provide both a more stringent and more real-world test than the
current test. The agency will address these uncertainties in the near
future. After it conducts research on tire aging and resistance to bead
unseating, it will conduct research on road hazard impact. Based on the
test results, it will decide whether to initiate rulemaking to adopt a
new or revised test.
Resistance to bead unseating--Instead of replacing the current bead
unseating test with a proposal based on a Toyota test, the agency is
retaining the bead unseating test and extending it to LT tires.
Industry previously recommended dispensing with a bead unseating test
because radial tires are easily able to satisfy the current one.
Results from the agency's 1997-1998 rollover testing provided a strong
rationale for upgrading, rather than deleting, the bead unseating test.
Post-NPRM agency testing data and public comments, however, called into
question whether the Toyota test provides both a more stringent and
more real-world test than the FMVSS No. 109 bead unseating test. The
agency will conduct research on bead unseating after conducting its
research on tire aging, and, based on the test results, decide whether
to initiate rulemaking to adopt a new or revised test.
Aging--At this time, the agency is not adopting a test to address
the deterioration of tire performance caused by aging. We proposed
three alternatives for an aging effects test that would expose tires to
the type of failures experienced by consumers at 40,000 kilometers or
beyond. Because we had little data and analysis regarding any of these
tests and understood the tire industry to be regularly conducting aging
testing, we requested comments on which alternative should be adopted.
The tire industry did not, however, disclose any of its testing data or
provide any analysis in its comments on the NPRM. However, some
industry members have recently begun a dialogue and offered to share
data with the agency.
In an attempt to gain a thorough understanding of existing aging
test mechanisms and methodologies, as well as data and analysis
relating to that testing, the agency is commencing its own research on
aging. The agency anticipates publishing a NPRM proposing an aging test
in approximately two years after this final rule.
Benefits
At the time of the NPRM, we were able to quantify only very slight
safety benefits. Given the reductions in several of our proposals and
the deferral of several of other proposals, the benefits of the final
rule will be less than we then projected. We now estimate 1 to 4 lives
saved and 23 to 102 injuries reduced. Nevertheless, the final rule will
increase the required level of performance for all tires and will
improve the strength, endurance, and heat resistance of the 5-11% of
tires that will have to be redesigned or modified to achieve
compliance.
Costs
Although in issuing the proposal we were able to estimate costs for
only two of the proposed tests, we estimated that those two tests alone
would result in costs of almost $300 million per year. However, given
the reductions in or deferrals of some of our proposals, we estimate
that the final rule will, in its entirety, result in annual costs for
new original equipment and replacement tires of $3.6 million to $31.6
million. The net costs per equivalent life saved will be about $5
million based on the mid-point of cost and discounted benefits
estimates.
Effective Dates/Implementation
The agency is providing a 4-year lead time for both tire and
vehicle manufacturers. All covered tires and vehicles must comply with
the amendments by June 1, 2007. In view of the comments by the tire and
vehicle industry regarding the extent and significance of design and
production changes that might have to be made as a result of changing
requirements in an area that has been not substantively revised in 30
years, NHTSA finds that an effective date of June 1, 2007 is more
reasonable than the shorter lead time proposed in the NPRM and is in
the public interest.
II. Background
A. The Transportation Recall Enhancement Accountability and
Documentation Act
Section 10, ``Endurance and Resistance Standards for Tires,'' of
the TREAD Act, Pub. L. 106-414, mandates that the agency issue a final
rule to revise and update its tire performance standards. However, the
Act gives the agency substantial discretion regarding the substance of
the final rule. The Act does not specify how the standards should be
revised or updated. For
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example, it does not specify which particular existing performance
requirements and test procedures should be improved or how much they
should be improved. Likewise, it does not specify which particular new
requirements should be added or how stringent they should be.
In response to section 10 of the TREAD Act, the agency
comprehensively examined possible ways of revising and updating its
tire standards. In doing so, it placed particular emphasis on improving
the ability of tires to withstand the effects of factors mentioned
during the consideration and enactment of the TREAD Act such as tire
heat build up, low inflation, and aging. The agency examined the value
of modifying the existing tests in its tire standards. In addition, it
examined the value of adopting several new tests.
B. Safety Problem
1. Outdated Performance Requirements
Prior to the enactment of the TREAD Act, the Firestone tire recalls
in 2000 focused public attention on the agency's passenger car tire
standard, FMVSS No. 109. The standard had not been substantively
revised since first issued over 30 years ago in 1967. At that time,
nearly all (more than 99 percent) of passenger car tires in the U.S.
were of bias, or bias belt construction. Accordingly, the requirements
and test procedures in FMVSS No. 109 were developed primarily to
address bias tires. Today, bias tires have been almost completely
replaced by radial tires on passenger cars and other light vehicles.
The use of radial tires has grown to the extent that they represent
more than 95 percent of passenger tires in both the U.S. and Europe and
are used on most other new light vehicles sold in the U.S.
NHTSA does not require that light vehicles be equipped with radial
tires, but regulates radial tire performance through FMVSS Nos. 109 and
119. Radial tires are less susceptible than bias ply tires to most
types of failures.\4\ Also, the switch to radial tire designs resulted
in significant improvements in tire performance compared with bias ply
tires. Given the superior performance of radial tires, it is easier for
them than for bias tires to comply with the requirements of FMVSS No.
109.\5\
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\4\ A radial passenger car tire carcass is typically made up of
one or two plies of cord material that run from bead to bead at an
angle of approximately 90 degrees to the centerline of the tire. As
a result, the cords do not crisscross. Because the cords do not
crisscross and because the opposite ends of each cord are anchored
to the beads at points that are directly opposite to each other, the
radial tire sidewall is more flexible than that of a bias tire and
the treadface is less flexible. The radial tire is reinforced and
stabilized by a belt that runs circumferentially around the tire
under the tread. This construction allows the sidewalls to act
independently of the belt and tread area when forces are applied to
the tire. This ``independent'' action is what allows the sidewalls
to readily absorb road irregularities without overstressing the
cords. Impact breaks caused by cord rupture do not occur in radial-
ply passenger car tires. This ``independent'' action also allows two
important things to happen during cornering: (1) The tread of a
radial tire remains fully in contact with the road over the entire
tread width, and (2) the ply cords and sidewall are able to absorb
the cornering forces without exerting the twisting force on the
beads that are exerted by bias constructions.
\5\ A bias passenger car tire carcass is typically made up of
two or four plies of cord material that run from bead to bead at an
angle of approximately 35 degrees to the centerline of the tire.
Alternating plies are applied at alternating angles during tire
manufacture so that the cord paths of alternating plies crisscross.
This type of construction provides a very strong, durable carcass
for the tire. However, it has drawbacks. Because the ply cords
crisscross and all the cords are anchored to the beads, the sidewall
is stiff and treadface is flexible. This type of construction
prevents different parts of the tire from acting independently of
one another when forces are applied to the tire. As a result, a bias
construction is susceptible to impact breaks because it does not
easily absorb road irregularities.
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While the durability and performance of tires have improved, the
conditions under which tires are operated have become more rigorous.
Higher speeds, greater loads, extended lifetimes of tires, longer
duration of travel \6\ and shifting demographics of vehicles sales \7\
have all contributed to much greater stresses and strains being placed
upon today's radial tires than those endured by earlier generation
radial tires.
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\6\ Passenger cars average 12,258 miles per year during the
first 6 years after purchase, while light trucks average 12,683
miles per year during the same time period. NPTS data also indicates
that minivans make the most person-trips per day, followed by SUVs,
passenger cars, and finally pickups. SUVs are estimated to make, on
average, 4.6% more person-trips per day than passenger cars. Also,
the 1995 Nationwide Personal Transportation Survey (NPTS) data set
suggests that the average light duty truck (LDT) (pickup trucks,
SUVs, and minivans) is used over longer distances and with more
people aboard than passenger cars. Additionally, SUVs are popular
for long distance weekend travel.
\7\ Americans have shifted toward a significantly higher use of
minivans, pickup trucks, and SUVs for personal travel. (Journal of
Transportation and Statistics, December 2000). Sales of light trucks
have risen steadily for over the past 20 years and now account for
almost half of the U.S. light vehicle market--more than twice their
market share as recently as 1983. (Industries in Transition, 1/01/
00; Journal of Transportation and Statistics, December 2000.) Sales
growth of heavier light trucks, those that have GVWRs above 6,000
pounds, increased at a much faster rate than their lighter
counterparts, with larger SUVs (6,000-10,000 pounds GVWR) showing an
average increase of 38 percent annually between 1990 and 1998.
Approximately 90 percent of these light trucks use passenger car
(P-metric) tires. The other 10 percent use light truck (LT) tires
load range C, D, or E tires, which are typically used on heavier
light trucks with a gross vehicle weight rating (GVWR) between 6,000
and 10,000 pounds. Continued growth in the sales and production of
light truck vehicles also drove the number of original equipment
light truck (LT) tires to a record high of approximately 8.4 million
units or a 25.2 percent increase over 1998's figures. (RMA 2000
Yearbook)
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The characteristics of a radial tire construction in conjunction
with present usage and purchasing patterns render the existing required
minimum performance levels in the high-speed test, endurance test,
strength test \8\, and bead-unseating test ineffective in
differentiating among today's radial tires with respect to these
aspects of performance.
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\8\ The FMVSS No. 109 plunger energy or strength test was
designed to evaluate the strength of the reinforcing materials in
bias ply tires, typically rayon, nylon or polyester, and it
continues to serve a purpose for these tires. However, a radial tire
is not susceptible to the kind of failure for which this test was
designed to prevent. The flexible sidewalls of radial tires easily
absorb the shock of road irregularities.
Because of the belt package, radial tires far exceed the
strength requirements of the test and many times the plunger bottoms
out on the rim instead of breaking the reinforcing materials in the
radial tire. During the years 1996 through 1998 RMA members reported
conducting nearly 19,000 plunger energy (strength) tests on radial
tires. There were no reported failures.
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2. Safety Problems Associated With Tires
Essentially, the size of the tire problem has remained the same
over the last eight years. With the increasing sales of light trucks,
and the fact that light trucks have more tire problems than passenger
cars, the problem has shifted more toward light trucks and away from
passenger cars. As discussed in the NPRM, several crash files contain
information on ``general'' tire related problems that precipitate
crashes. The more recent of these files are the National Automotive
Sampling System--Crashworthiness Data System (NASS-CDS) \9\ and the
Fatality Analysis Reporting System (FARS).\10\
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\9\ For the NASS-CDS system, trained investigators collect data
on a sample of tow-away crashes around the country. These data can
be ``weighted up'' to national estimates. A NASS-CDS General Vehicle
Form contains the following information: a critical pre-crash event,
such as vehicle loss of control due to a blowout or flat tire. This
category includes only part of the tire-related problems that cause
crashes. This coding would only be used when the tire went flat or
there was a blowout that caused a loss of control of the vehicle,
resulting in a crash.
\10\ In FARS, tire problems are noted after the crash, if they
are noted at all. The FARS file does not indicate whether the tire
problem caused the crash, influenced the severity of the crash, or
just occurred during the crash. For example, some crashes may have
been caused by a tire blowout, while in others the vehicle may have
slid sideways and struck a curb, causing a flat tire that may or may
not have influenced whether the vehicle experienced rollover. Thus,
while an indication of a tire problem in the FARS file give some
indication as to the potential magnitude of the tire problem in
fatal crashes, it can neither be considered the lowest possible
number because the tire might not have caused the crash, nor the
highest number of cases because not all crashes with tire problems
might have been coded by the police.
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NASS-CDS data for 1995 through 1998 \11\ indicate that there are an
estimated 23,464 tow-away crashes per year coded by the NASS
investigators (relying on the police report of the crash) as having
been caused by blowouts or flat tires. Based on that estimate, about
one-half of one percent of all crashes are caused by these tire
problems. The rate of blowout-caused crashes for light trucks (0.99
percent) is more than three times the rate of those crashes for
passenger cars (0.31 percent). Blowouts cause a much higher proportion
of rollover crashes (4.81) than non-rollover crashes (0.28), and more
than three times the rate in light trucks (6.88 percent) than in
passenger cars (1.87 percent).
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\11\ Based on the consistency in the overall numbers of tire
problems in FARS during the past eight years, the agency has not
deemed it necessary to update the injury numbers in the more
intricate analysis of NASS-CDS data. We believe that there would be
almost no change in the target population if a few more recent
years, e.g., 1999-2001, were included in the NASS-CDS analysis.
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FARS data for 1999 through 2001 show that 1.10 percent of all light
vehicles in fatal crashes were coded by investigators as having had
tire problems. Light trucks had slightly higher rates of tire problems
(1.34 percent) than passenger cars (0.92 percent). The annual average
number of vehicles with tire problems in FARS was 528 (255 passenger
cars and 273 light trucks).
A further examination of the FARS data indicates that heat is a
factor in tire problems. An examination of two surrogates for heat, the
region of the U.S. in which the crash occurred, and the season in which
the crash occurred, indicates that the highest rates of tire problems
occurred in light trucks in southern states in the summertime, followed
by light trucks in northern states in the summertime, and then by
passenger cars in southern states in the summertime. The lowest rates
occurred in winter and fall. Based on these data, tires on light trucks
appear to be more affected by higher ambient temperatures than tires on
passenger cars.
Examining tire problems in the NASS-CDS from 1992 to 1999 by types
of light trucks and vehicle size indicates that LT tires used on light
trucks exhibited more problems than P-metric tires. LT tires are used
on vehicle classes identified for this analysis as Van Large B and
Pickup Large B groups of vehicles. These groups of vehicles typically
consist of the \3/4\-ton and 1-ton vans and pick-ups. P-metric tires
are used on most of the other light trucks. The data indicate that the
average percentage of light trucks in the NASS-CDS having a LT tire
problem is 0.84, while the average percent of light trucks having a P-
metric tire problem is 0.47 percent. These larger pickups and vans,
however, carry heavier loads and may be more frequently overloaded than
lighter trucks. In addition, these heavier vehicles are often used at
construction sites and may be more apt to encounter nail punctures and
experience flat tires. Thus, there may be usage issues that increase
the percentage of tire problems for these larger trucks, rather than
exclusively a qualitative difference between P-metric and LT tires.
C. Existing NHTSA Performance Requirements for Tires
The following discussion summarizes existing NHTSA requirements
relating to tires.
FMVSS No. 109, New pneumatic tires, 49 CFR 571.109, specifies the
requirements for all tires manufactured for use on passenger cars
manufactured after 1948. This standard, which was issued in 1967 under
the National Traffic and Motor Vehicle Safety Act (Safety Act),
specifies dimensions for tires used on passenger cars and requires that
the tires meet specified strength, resistance to bead unseating,
endurance, and high speed requirements, and be labeled with certain
safety information. FMVSS No. 109 applies to passenger car (P-metric)
tires produced for use on passenger cars, multipurpose passenger
vehicles (MPV), and light trucks (sport utility vehicles (SUV), vans,
minivans, and pickup trucks). The standard was adopted from the Society
of Automotive Engineers (SAE) recommended practice J918c, Passenger Car
Tire Performance Requirements and Test Procedures, which was first
issued by the SAE in June 1965.\12\ The current FMVSS No. 109 includes
four performance requirements for tires:
---------------------------------------------------------------------------
\12\ SAE is an organization that develops voluntary standards
for aerospace, automotive and other industries. Many of SAE's
recommended practices are developed using technical information
supplied by vehicle manufacturers and automotive test laboratories.
---------------------------------------------------------------------------
[sbull] A strength test, which evaluates the strength of the
reinforcing materials in the tire;
[sbull] A resistance-to-bead unseating test, which evaluates how
well the tire bead is seated on the rim (regulating the tire-rim
interface guards against sudden loss of tire air pressure when a tire
is subjected to lateral forces such as during severe turning
maneuvers);
[sbull] An endurance test, which evaluates resistance to heat
buildup when the tire is run at or near its rated load nonstop for a
total of 34 hours; and
[sbull] A high-speed test, which evaluates resistance to heat
buildup when the tire is run at 88 percent of its maximum load at
speeds of 75 mph, 80 mph, and 85 mph for 30 minutes at each speed.
For the purposes of testing tires to determine their compliance
with these requirements, the standard specifies values for several
factors, such as tire inflation pressure, the load \13\ on the tire,
and the rim on which a tire is mounted. The standard specifies
permissible inflation pressures (or wheel sizes, in the case of bead
unseating test) to facilitate compliance testing. The standard requires
that each passenger car tire have a maximum permissible inflation
pressure labeled on its sidewall (S4.3). Section 4.2.1(b) lists the
permissible maximum pressures: 32, 36, 40, or 60 pounds per square inch
(psi) or 240, 280, 290, 300, 330, 340, 350, or 390 kiloPascals (kPa). A
manufacturer's selection of a maximum pressure has the effect of
determining the pressures at which its tire is tested. For each
permissible maximum pressure, Table II of the standard specifies
pressures at which the standard's tests must be conducted. The intent
of this provision is to limit the number of possible maximum inflation
pressures and thereby reduce the likelihood of having tires of the same
size on the same vehicle with one maximum load value, but with
different maximum permissible inflation pressures.
---------------------------------------------------------------------------
\13\ Load percentages stated throughout this document, unless
otherwise specified, are based on the sidewall maximum rated load.
---------------------------------------------------------------------------
Closely related to FMVSS No. 109 is FMVSS No. 110, Tire selection
and rims, 49 CFR 571.110. FMVSS No. 110 requires that each passenger
car be equipped with tires that comply with FMVSS No. 109, that tires
on the cars be capable of carrying the maximum loaded vehicle weight,
that the rims on the car be appropriate for use with the tires, and
that certain information about the car and its tires appear on a
placard in the passenger car. FMVSS No. 110 also specifies rim
dimension requirements and further specifies that, in the event of a
sudden loss of inflation pressure at a speed of 97 km/h (60 mph), rims
must retain a deflated tire until the vehicle can be stopped with a
controlled braking application. FMVSS No. 110 initially became
effective in April 1968.
FMVSS No. 117, Retreaded pneumatic tires, 49 CFR 571.117,
establishes performance, labeling, and
[[Page 38121]]
certification requirements for retreaded pneumatic passenger car tires.
Among other things, the standard requires retreaded passenger car tires
to comply with the tubeless tire resistance to bead unseating and the
tire strength requirements of FMVSS No. 109. FMVSS No. 117 also
specifies requirements for casings to be used for retreading, and
certification and labeling requirements.
FMVSS No. 119, New pneumatic tires for vehicles other than
passenger cars, 49 CFR 571.119, specifies performance and labeling
requirements for new pneumatic tires designed for highway use on
multipurpose passenger vehicles, trucks, buses, trailers and
motorcycles manufactured after 1948, and requires treadwear indicators
in tires, and rim matching information concerning those tires. Under
this standard, each tire must meet requirements that are qualitatively
similar to those in FMVSS No. 109 for passenger car tires. The high
speed performance test in this standard only applies to motorcycle
tires and to non-speed-restricted tires of 14.5-inch nominal rim
diameter or less marked load range A, B, C, or D. In addition, FMVSS
No. 119 does not contain a resistance-to-bead unseating test.
A tire under FMVSS No. 119 is generally required to meet the
performance requirements when mounted on any rim listed as suitable for
its size designation in the publications, current at the time of the
tire's manufacture, of the tire and rim associations that are listed in
the standard. Further, the tire is required to meet the dimensional
requirements when mounted on any such rim of the width listed in the
load-inflation table s of this standard. In addition to the permanent
marking for any non-matching listed rims, each tire manufacturer is
required to attach to the tire, for the information of distributors,
dealers and users, a label listing the designations of rims appropriate
for use with the tire.
FMVSS No. 120, Tire Selection and rims for motor vehicles other
than passenger cars, 49 CFR 571.120, requires that vehicles other than
passenger cars equipped with pneumatic tires be equipped with rims that
are listed by the tire manufacturer as suitable for use with those
tires and that rims be labeled with certain information. It also
requires that these vehicles shall be equipped with tires and rims that
are adequate to support the vehicle's certified gross weight.
Tire selection under FMVSS No. 120 consists of two elements. With
one exception, each vehicle must be equipped with tires that comply
with FMVSS No. 119 and the load rating of those tires on each axle of
the vehicle must together at least equal the gross axle weight rating
(GAWR) for that axle. If the certification label lists more than one
GAWR-tire combination for the axle, the sum of the tire's maximum load
ratings must meet or exceed the GAWR that corresponds to the tire's
size designation. If more than one combination is listed, but the size
designation of the actual tires on the vehicle is not among those
listed, then the sum of the load ratings must simply meet or exceed the
lowest GAWR that does appear.
FMVSS No. 120 also contains a requirement related to the use of
passenger car tires on vehicles other than passenger cars. The
requirement states that when a tire that is subject to FMVSS No. 109 is
installed on a multipurpose passenger vehicle, truck, bus, or trailer,
the tire's load rating must be reduced by a factor of 1.10 by dividing
by 1.10 before determining whether the tires on an axle are adequate
for the GAWR. This 10 percent de-rating of P-metric tires provides a
greater load reserve when these tires are installed on vehicles other
than passenger cars. The reduction in the load rating is intended to
provide a safety margin for the generally harsher treatment, such as
heavier loading and possible off-road use, that passenger car tires
receive when installed on a MPV, truck, bus or trailer, instead of on a
passenger car.
FMVSS No. 129, New non-pneumatic tires for passenger cars, 49 CFR
571.129, includes definitions relevant to non-pneumatic tires and
specifies performance requirements, testing procedures, and labeling
requirements for these tires. To regulate performance, the standard
contains performance requirements and tests related to physical
dimensions, lateral strength, strength (in vertical loading), tire
endurance, and high-speed performance. The performance requirements and
tests in FMVSS No. 129 were based upon those contained in FMVSS No.
109.
III. Pre-TREAD Act Enactment Agency Response to Safety Problem
Prior to this rulemaking, NHTSA embarked on a program of global
harmonization for light vehicle tire standards under the auspices of
the United Nations/Economic Commission for Europe's (UN/ECE) World
Forum for Harmonization of Vehicle Regulations (WP.29).\14\ NHTSA,
within the WP.29's Working Party on Brakes and Running Gear (GRRF),\15\
had been working cooperatively with other countries to develop a global
tire standard that could better assess the safety performance of modern
tires.
---------------------------------------------------------------------------
\14\ Formerly, ``Working Party on the Construction of Vehicles
(WP.29).'' The Forum's Web site is http://frwebgate.access.gpo.gov/cgi-bin/leaving.cgi?from=leavingFR.html&log=linklog&to=http://www.unece.org/trans/main/welcwp29.htm
.
\15\ The GRRF is a Working Party within WP.29 that is
responsible for developing draft global technical regulations on
brakes, tires, wheels, and other chassis components of motor
vehicles.
---------------------------------------------------------------------------
Beginning in July 1999, the GRRF had been considering a draft
global technical regulation (GTR) based on the Global Tire Standard
2000 for New Pneumatic Car Tires (GTS-2000),\16\ \17\ an industry
developed standard. Prior to the enactment of the TREAD Act, tentative
consensus within an ad hoc tire harmonization working group of the GRRF
concerning the draft GTR had been reached on the following issues: (1)
to adopt the ECE R30 high speed test methodology (see Note) in place of
the FMVSS No. 109 high speed test, (2) to keep the current FMVSS No.
109 resistance-to-bead unseating test until NHTSA develops an
alternative that is more appropriate for radial tires, and (3) to
develop an optional requirement for testing wet grip.
---------------------------------------------------------------------------
\16\ \17\ GTS-2000 would replace the current FMVSS
No. 109 high-speed test with the high-speed test required by ECE--
R30 (the European tire regulation for tires used on light passenger
vehicles), including temporary spares. It would also limit the
application of the other three tests currently required by FMVSS No.
109, namely the strength test, the bead unseating test, and the
endurance test, to bias tires and low speed rated radial tires
because industry believes that these three tests have relevance to
bias and bias-belted tires, but little, if any, relevance to radial
tires, with the single exception of the endurance test for low speed
(160 km/h/99 mph, or less) radial tires.
Note: The ECE Regulation 30 includes a single performance
requirement, the high-speed test, which is conducted at a speed
close to and up to the rated speed of the tire. The methodology used
in ECE R30 and suggested by the tire industry in GTS-2000 for tire
harmonization determines the test speed based on the tire's speed
symbol rated speed. The following chart illustrates the rated speed
in km/h for each speed symbol.
------------------------------------------------------------------------
Rated speed--
Speed symbol km/h
------------------------------------------------------------------------
F..................................................... 80
G..................................................... 90
J..................................................... 100
K..................................................... 110
L..................................................... 120
M..................................................... 130
N..................................................... 140
P..................................................... 150
Q..................................................... 160
R..................................................... 170
S..................................................... 180
T..................................................... 190
[[Page 38122]]
U..................................................... 200
H..................................................... 210
V..................................................... 240
W..................................................... 270
Y..................................................... 300
ZR.................................................... 300
------------------------------------------------------------------------
These speeds range from a minimum of 140 km/h (88 mph) to 300
km/h (188 mph) for W, Y categories. The total test time is 50
minutes. The inflation pressures for the ECE R30 high-speed test are
typically much higher than those recommended by vehicle
manufacturers for vehicle operation.
Other issues that had also been under discussion in the ad hoc
group prior to the TREAD Act included: (a) the U.S.'s suggestion to
lower the inflation pressures for and increase the duration of the high
speed test (current ECE R30 test), (b) the U.S.'s suggestion to agree
on the need for tire labeling requirements that are unique to the U.S.,
such as maximum inflation pressure, and UTQG consumer information, (c)
the U.S.'s suggestion to identify requirements that should be included
as optional requirements, (d) assigning to the UN the responsibility
for tire plant code registration for a global standard, and (e) the
U.S.'s suggestion to increase the ambient temperature for the high
speed test.
In a February 2001 submission to the docket (Docket No. NHTSA-2000-
8011), the Chairman of the GRRF Tire Harmonization Working Group had
recommended on behalf of the GRRF that NHTSA adopt a draft text that
reflects the current state of deliberations for developing a harmonized
tire standard. At its 126th session in March 2002, WP.29 decided that
there was little prospect of achieving global agreement at this stage
and suspended further work indefinitely. The group, as its final task,
submitted comments on the NPRM in this rulemaking. The U.S.
representative to the GRRF recused himself from these deliberations.
IV. Post-TREAD Act Enactment Agency Response to Safety Problem
A. Tire Testing and Opening of Docket No. 2000-8011
Shortly after the enactment of the TREAD Act, the agency had
initiated tire testing at Standards Testing Labs (STL) in November 2000
to evaluate the high-speed performance, endurance performance, and low
inflation pressure performance of a limited number of current
production tires. The agency had developed a test matrix which focused
on the five main parameters currently used in tire testing under FMVSS
Nos. 109 and 119: load, inflation pressure, speed, duration, and
ambient temperature. Copies of the test matrix and testing results for
P-metric tires and for LT tires have been available in the docket (see
the Tire Test Matrix in NHTSA Docket No. 2000-8011-1).
In summary, the results of the high speed and endurance tests had
indicated that the agency could develop and propose test requirements
that were realistic in terms of the test parameters, yet more stringent
than the current FMVSS No. 109, FMVSS No. 119 requirements, European
Regulation ECE R 30, GTS 2000, and RMA 2000. The proposed test
requirements had differentiated tires with better high speed and
endurance performance from those with lesser performance. The low
pressure validation tests had indicated that tires that were able to
successfully complete the endurance testing could also complete an
additional 90-minute test at a low inflation pressure, 140 kPa for P-
metric tires, thus providing an adequate safeguard for consumers to
take corrective action when the low pressure warning lamp proposed
under the tire pressure monitoring system rulemaking is activated at a
``significantly'' under-inflated level.
In September 2000, NHTSA had opened a docket, NHTSA-2000-8011,
titled ``Tire Testing--Federal Motor Vehicle Safety Standard (FMVSS No.
109).'' The purpose of this docket has been to collect tire test data
and receive feedback on its high speed and endurance performance
testing matrices. At issuance of the NPRM, comments and recommendations
from 7 entities had been received in the docket. Additionally, Toyota
Motor Company (Toyota) had submitted a copy of its air loss test
procedure to the docket. Substantive comments and recommendations in
response to NHTSA's testing matrices were discussed in the NPRM.
B. March 5, 2002, Notice of Proposed Rulemaking (NPRM)
As a result of the aforementioned testing and data collection
efforts, the agency identified an array of amendments for revising and
updating its tire standards and thereby improving tire performance in a
NPRM published on March 5, 2002. Some of these amendments would have
upgraded existing tests, while the others would have added new ones.
In the NPRM, the agency proposed to include the new tire
performance requirements in Standard No. 139, a new tire standard
established in a November 18, 2002 final rule on Tire Safety
Information (Docket No. NHTSA-02-13678, 67 FR 69600, November 18,
2002). The standard applies to light vehicle tires. As used in the tire
safety information final rule, ``light vehicles'' are vehicles (except
motorcycles) with a gross vehicle weight rating (GVWR) of 10,000 pounds
or less.
Under the NPRM, the new standard would have contained requirements
and test procedures addressing the following aspects of tire
performance: Tire dimension, high speed, endurance, road hazard impact,
bead unseating, low inflation pressure performance, and aging
effects.\18\
---------------------------------------------------------------------------
\18\ For the convenience of the reader, we have placed in the
docket for today's final rule a document that shows how the recently
promulgated tire safety information requirements (see Footnote
1) and performance requirements appear together in FMVSS
No. 139.
---------------------------------------------------------------------------
The proposed high speed and endurance tests would have replaced the
current high speed and endurance tests in FMVSS No. 109, New Pneumatic
Tires--Passenger Cars, 49 CFR 571.109, with a more stringent
combination of testing parameters (ambient temperature, load, inflation
pressure, speed, and duration.) Most significantly, the proposed high
speed test would have specified test speeds (140, 150 and 160 km/h (87,
93, and 99 mph)) that are substantially higher than those currently
specified in FMVSS No. 109 (120, 128, 136 km/h (75, 80, 85 mph)).
Likewise, the proposed endurance test would have specified a test speed
50 percent faster (120 km/h (75 mph)) than that currently specified in
FMVSS No. 109 (80km/h (50 mph)), as well as a duration 6 hours longer
(40 hours total) than that currently specified in FMVSS No. 109 (34
hours total). At the specified test speed (120 km/h), the proposed
endurance test distance (4800 km) would have been almost double the
distance accumulated than under the current endurance test (2720 km at
80 km/h). These new testing parameters were based on NHTSA's activities
undertaken in response to the TREAD Act, including extensive agency
testing, data gathering and analyses as well as agency review of other
existing international, industry and National standards and proposals,
and submissions by the public.
The proposed road hazard impact test and the bead unseating test
were modeled on SAE Recommended Practice J1981, Road Hazard Impact Test
for Wheel and Tire Assemblies (Passenger Car, Light Truck, and
Multipurpose Vehicles), and the Toyota air loss test, respectively.
These new tests would have replaced the strength and bead unseating
resistance tests in the current FMVSS No. 109 with tests
[[Page 38123]]
that were believed to be more real-world and stringent.
In addition to the tests cited above, the proposed standard would
have contained tests for two new aspects of performance: Low inflation
pressure performance and aging effects. By seeking to establish tests
for these aspects of performance, the agency was attempting to address
concerns raised by members of Congress in hearings preceding the
enactment of the TREAD Act that NHTSA's current test requirements do
not evaluate how well tires perform either when significantly
underinflated or after being in use for several years and being
subjected to environmental variables, such as heat. In particular,
underinflation and heat were factors highlighted as contributing to
failure of the Firestone ATX and Wilderness tires in the TREAD
hearings, and in the agency's Firestone investigation (NHTSA Office of
Defects Investigation (ODI) investigation number EA00-023).
To test low inflation pressure performance, the agency proposed two
alternative tests based on agency testing and data analyses. Both tests
would have evaluated tires when they are significantly under-inflated.
For instance, 140 kPa (20 psi) for P-metric tires (the low inflation
pressure threshold requirement for warning lamp activation in the
proposed Tire Pressure Monitoring System (TPMS) standard, Docket No.
NHTSA-00-8572 (66 FR 38982, July 26, 2001) would have been used as the
``inflation pressure'' testing parameter for standard load P-metric
tires. To test for resistance to aging effects, the agency proposed
three alternative tests that would have evaluated a tire's long term
durability through methods different than and/or beyond those required
by both the current and the proposed endurance test parameters. The
three tests would have used peel strength testing, long-term durability
endurance requirements, and oven aging, respectively. The agency
solicited comments on which of the two proposed tests for addressing
low inflation pressure performance, and which of the three tests
proposed for addressing aging effects, should have been chosen for the
new standard.
In addition to proposing test procedures for the new standard, the
agency also discussed in this document its ongoing and future research
plans on tire safety, and sought comments on the future use of
shearography analysis (a method of analysis using laser technology) for
evaluating the condition of tires subjected to the proposed testing
procedures and the plans for revising the Uniform Tire Quality Grading
Temperature Grading Requirement testing speeds so that they would have
been consistent with the test speeds in the proposed high speed tests.
With regard to tire selection criteria and the de-rating of P-
metric tires, the agency proposed retaining the de-rating percentage of
1.10 for P-metric tires used on non-passenger car vehicles and revising
FMVSS No. 110 to require that the determination of vehicle normal load
(``reserve load'') on the tire be based on 85% of the load at vehicle
placard pressure.
Finally, the agency discussed revising FMVSS Nos. 110, Tire
selection and rims, for passenger cars, 49 CFR 571.110, and 120, Tire
selection and rims for motor vehicles other than passenger cars, 49 CFR
571.120, to reflect the applicability of the proposed light vehicle
tire standard to vehicles up to 10,000 pounds GVWR, and revising FMVSS
Nos. 117, Retreaded pneumatic tires, 49 CFR 571.117, and 129, New non-
pneumatic tires for passenger cars, 49 CFR 571.129, to replace the
performance tests which reference or mirror those in FMVSS No. 109 with
those specified in the proposed new light vehicle tire standard.
Emphasizing that the agency was mindful of the principles for
regulatory decisionmaking set forth in Executive Order 12866,
Regulatory Planning and Review, and wished to adopt only those
amendments that contribute to improved safety, NHTSA carefully examined
the benefits and costs of these amendments. The agency noted that its
efforts to do so, however, were limited by two factors: (1) The limited
time allowed by the schedule specified in the TREAD Act for completing
this rulemaking, and (2) the difficulty inherent in crash avoidance
rulemakings, stemming from the multiplicity of the factors contributing
to the occurrence of any crash and the difficulty of ascertaining the
relative contribution of each factor, in linking specific improvements
in safety requirements with specific reductions in crashes and
resulting deaths and injuries.
The agency, based on the proposed high speed and endurance test,
estimated that the benefits of this would have been 27 lives saved and
667 injuries reduced and emphasized that not all benefits could have
been quantified, e.g., benefits from the proposed aging test, the
proposed low inflation pressure performance tests, the proposed road
hazard and bead unseating tests, and aspects of the proposal that
address the overloading of vehicles.
The agency estimated that about one-third (32.8 percent) of all
tires would have needed improvements to pass the high speed and
endurance tests and that the overall annual cost of these tests for new
original equipment (64 million tires) and replacement tires (223
million tires) would have been estimated at $282 million for a total of
287 million tires sold annually and the net costs per equivalent life
saved would have been about $7.2 million. The agency noted that it
anticipated receiving cost data and other information that would enable
it to refine its assessment of benefits and costs.
Expressing concern about the overall costs of the rulemaking and
the net costs per equivalent life saved, the agency sought comments on
the proposed new standard, including its applicability and test
procedures, modifications to related existing standards, and lead time
provided for manufacturers to achieve compliance.
C. Post-NPRM Technical Submissions to NHTSA Tire Upgrade Docket
1. NHTSA Testing at Standards Testing Labs (STL)
The agency conducted tire testing at Standards Testing Labs (STL)
to evaluate the performance of tires tested to the high speed and
endurance parameters proposed in the NPRM. The agency tested 20 (15 P-
metric and 5 LT) current production tires.
For high speed testing, at an ambient temperature of 38[deg] C, all
20 tires tested for a duration of 30 minutes at 140, 150, and 160 km/h
with the proposed inflation pressures completed the test without
failure. At an ambient temperature of 40[deg] C with the other
parameters being the same, all 15 P-metric tires completed the test
without failure. For LT tires, 1 of 5 tires tested failed the high-
speed test. Testing to these same conditions during Winter 2002 with 40
P-metric and 20 LT tires resulted in failures in 2 P-metric tires and 0
LT tires.
Endurance testing was conducted with the same parameters proposed
in the NPRM--load combinations of 90/100/110 percent load, test speeds
of 120 km/h, duration of 40 hours, ambient temperature of 40 C, and the
inflation pressure of 180 kPa for P-metric tires and 75 percent of
maximum inflation pressure for LT tires. Four of 15 tires failed to
complete the test, representing a 27 percent failure rate. The same 15
tire brands were tested at the same parameters except the ambient
temperature was reduced to 38[deg] C and the loads were reduced to 85/
90/100 percent. Under these conditions, 1 of
[[Page 38124]]
the 15 tires failed to complete the test, representing a failure rate
of 7 percent. The one failure was a ``Q'' speed-rated snow tire that
completed the 40-hour duration but failed the post-inspection because
of chunking.
For the 5 LT tires tested, 3 of the 5 completed the endurance tests
at the proposed parameters, representing a 40 percent failure rate.
When the load and ambient temperature were reduced to 85/90/100 percent
and 38[deg] C, respectively, all 5 LT tires completed the test without
any failures.
The agency also conducted low pressure testing at Smithers
Scientific to evaluate Alternative 2 of the proposed low pressure test
on the performance of 13 tires (10 P-metric and 3 LT).\19\ The proposed
40-hour endurance test was performed on the tires before they were run
to the low pressure test. The low pressure test parameters included an
inflation pressure of 140 kPa, a speed of 140, 150, 160 km/h, a
duration of 90 minutes (30 minutes at each test speed), a 67 percent
load. The same tests were performed using 3 LT tires, but at inflation
values of 260/340/410 kPa for load ranges C/D/E, respectively. These
inflation pressure values represent the lowest inflation pressure
provided by tire industry standardizing bodies for a tire load limit.
---------------------------------------------------------------------------
\19\ The agency did not re-test any tires to Alternative 1 of
the low pressure endurance performance test since earlier testing
(in Spring 2001) of 24 tires that completed a more stringent
endurance test (50 hours and loads of 100/110/115 percent indicated
no failures.
---------------------------------------------------------------------------
One of the P-metric tires failed to complete the endurance test
and, therefore, was not tested to the low pressure test. The 12
remaining tires tested completed the 90-minute low inflation test
without failure.
2. Rubber Manufacturer's Association (RMA) Design of Experiment (DOE)
and Confirmation Testing
Members of the RMA developed a response surface model Design of
Experiment (DOE) to assess tire temperatures versus test conditions
(inflation pressure, load, and speed), surface type (standard test
wheel of 1.7-m diameter versus a flat surface), and ambient
temperature. An additional follow-up confirmation round of testing,
which contained a broader range of tire types and sizes, was also
conducted by RMA.\20\
---------------------------------------------------------------------------
\20\ An additional follow-up confirmation round of testing,
containing a broader range of tire types and sizes, was conducted to
validate the results of the DOE. RMA ran a matrix of passenger and
light truck tires on high speed (increasing speed in 10 km/h steps
to failure) and endurance (increasing load in 10% steps to failure).
Seven high-volume, representative tire sizes of various brands were
included in the test protocol (4 passenger and 3 light truck). Each
tire size was tested for high speed and endurance; a total of 145
tires were tested. Passenger tire sizes tested included: P235/75R15
for economy all-season; P215/70R15 for standard load ``broad-line'';
P265/75R16 for all-terrain; and, P215/70R15 for snow. The light
truck sizes tested included: LT245/75R16 LRE for all-terrain/all-
traction; LT235/85R16 LRE for all-season; and, 31 x 10.5 R15 LRC for
mud.
---------------------------------------------------------------------------
RMA tested P-metric and LT tires to a matrix of high speed and
endurance tests. Seven (4 P-metric and 3 LT) tire sizes of various
brands were included in the test protocol. P-metric tires included
P235/75R15 for all season, P215/70R15 for standard load ``broad line,''
P265/75R16 for all terrain, and P215/70R15 for snow. For LT tires, the
sizes were LT245/75R16 LRE for all-terrain/all-traction, LT 235/85R16
LRE for all season, and 31 x 10.5 R 15 LRC for mud. A total of 145
tires were tested.
The parameters RMA used for its high speed testing for P-metric
tires were identical to the agency's, except for the ambient
temperature. For LT tires, RMA's test parameters were 10 km/h lower
than the agency's proposal for speed (130, 140, 150 km/h), and higher
for inflation pressures at 330 and 520 kPa for load ranges C and E
tires, respectively. All 42 P-metric tires tested to RMA's proposal
completed the 160 km/h step without any failures. Of the 32 LT tires
tested, 1 tire failed to complete the 150-km/h step, representing a 3
percent failure rate, and 2 LT tires failed to complete the 160 km/h
speed step, a 6 percent failure rate.
For its endurance test parameters for P-metric tires, RMA utilized
an ambient temperature at 38[deg] C, a load at 85/90/100 percent of the
maximum load rating, the same test speed proposed in the NPRM (120 km/
h) and duration at 34 hours. For LT tires, RMA's testing included the
same parameters as those for P-metric tires except it utilized a lower
test speed of 110 km/h and higher inflation pressures at 285 and 445
kPa for load ranges C and E tires, respectively. For the 30 P-metric
tires tested to RMA's endurance test, 2 failed to complete the 100
percent load step (5 percent failure rate). For LT tires, 2 of 32 tires
tested failed to complete the 100 percent load step (6 percent failure
rate).
The outline of RMA's DOE text matrix, including specific test
conditions applied by tire type, as well as a full set of DOE tables,
charts, graphs, and data are included as DOE Attachment II to RMA's
comments (Docket No. 2000-8011-64).
According to RMA, tires included in the test matrix were selected
to cover the appropriate range of technical parameters and to ensure
representative high volume in the marketplace. The three ``popular''
tire sizes chosen by RMA were: (1) P205/65R15, (2) P235/75R15, and (3)
LT245/75R16 LRC/LRE. Most of the tires tested by RMA, particularly
those used for the confirmation testing, were at the lower end of the
speed rating scale, e.g. ``Q'' through ``S'' and included snow tires,
which represent a small percent of sales of replacement tires in the
U.S. A brief summary of RMA's DOE conclusions and recommendations are
briefly discussed below. RMA's recommendations and comments on the NPRM
proposals are summarized in the following section of this document.
In summary, the RMA concluded from the DOE and confirmation test
results that:
(1) Speed is the most dominant test parameter. Larger temperature
increases are observed when speed is increased compared to changing
inflation pressure or load, particularly on a test wheel. According to
the DOE, at 80 km/h the average tire temperature is 2[deg] C higher on
a 1.7 m test wheel than a flat surface, at 160 km/h the curved surface
is 25[deg] C higher.
(2) Passenger car and light truck tires require different test
conditions on a test wheel, particularly for speed, to achieve
comparable levels of severity. The effect of this curved surface of the
1.7 m test wheel is to increase the tire deflection compared to a flat
surface. In addition, the combination of the curvature of the tire and
reverse curvature of the test wheel results in the footprint of the
tire being altered. The footprint shape is altered in a non-
representative manner when compared to a flat surface. This altered
deflection and footprint area result in substantially higher stresses.
This is demonstrated by the higher tire temperatures on a curved versus
flat surface.
(3) The effect of the test wheel curvature increases substantially
with speed. Standing waves, which lead to early tire failure, occur at
speeds 10 to 20 km/h lower on a curved surface compared to flat. To
have a realistic test that can be related to real-world conditions, it
is important to properly adjust test conditions on a curved surface to
as closely as possible match those of a flat surface.
3. Ford Motor Company (Ford) Tire Aging Analysis
In June 2002, Ford presented its analysis on the effectiveness of
the aging protocols proposed by NHTSA for FMVSS No. 139. Ford's
presentation was comprised of evaluated results obtained from tire
investigations and data analysis from experiments based on
[[Page 38125]]
the parameters discussed in the Notice. Based on the results from these
experiments, Ford recommended aging mounted tires with a 50/50 blend of
oxygen/nitrogen in an oven for two weeks followed by a peel test to be
performed on the tire. They also suggested that it would be more
appropriate to test the endurance, high speed, or low pressure
performance of a tire aged in this manner.
Ford's observations and conclusions are summarized below:
Results Obtained From Tire Investigations: (1) There is a very
strong correlation between cross-link density and peel strength for all
of the manufacturing facilities, (2) peel strength decreases
exponentially as, over time, cross-link density increases (as cross-
link density increases, the elongation at break decreases), (3) since
there is a relationship between cross-link density and peel strength,
and also a relationship between peel strength and age of the tire, a
relationship between cross-link density and age of the tire should also
exist, (4) the evidence that cross-link density exponentially increases
over time suggests that skim and wedge rubber is aging oxidatively, and
(5) the aging mechanism of spare tires is the same as road tires,
oxidative.
Results From NHTSA ODI Report on Firestone Wilderness AT Tires: (1)
The overwhelming majority of tires analyzed aged oxidatively in the
field and oxidative aging is the predominant mechanism in the reduction
of peel strength over time.
Adhesion (Peel) Test: (1) Although peel testing is an important
characteristic of tires, the data for Alternative 1 do not support the
use of endurance testing as an appropriate aging condition for the tire
because the test procedure does not influence the peel strength to any
significant degree, i.e., after 24 hours of testing, only a 10% decline
in peel strength is affected, while after 50 hours, a 16.8% decrease is
measured, (2) the cross-link density of the skim rubber becomes lower
as a result of the conditions at which the endurance test is run and
this indicates that anaerobic aging due to severe heat and stress is
degrading the rubber properties, (3) field aged tires increase in
cross-link density with time, not decrease, (4) the wedge properties of
the endurance tested tires also show anaerobic aging and this data
shows that significant anaerobic aging occurs during endurance testing
of this tire, (5) the field data obtained by both NHTSA and Ford
suggest aerobic/oxidative aging.
Michelin's Long-Term Durability Endurance Test: (1) The test is not
an appropriate universal aging test because it does not properly age
the wedge region of larger tires or tires with a heavier tread mass (in
the late 1970s and early 1980s when this test was first developed,
tread patterns were more all season than all terrain and the average
tire size was smaller), (2) the dynamic aspect of the test is too
benign for the nearly 10.5 days of test wheel time required (for
passenger car tires, running the tire slightly overloaded (11%) and
significantly overinflated (17%--significant because inflation pressure
changes have a more pronounced effect than load changes in test wheel
tests) at 97 km/h essentially prolongs the test so that oxidative aging
can occur but fails to test the belt package in any meaningful way once
it is aged), (3) the test is not without merit; the 50/50 oxygen/
nitrogen blend does accelerate the oxidative aging mechanism of skim
rubber.
Oven Aging: (1) Oven aging tires, either un-mounted or mounted with
air, has very little effect on the chemical and physical properties of
the belt package rubber; only when mounted with the 50/50 blend do
properties significantly change, (2) it is possible, by using the 50/50
oxygen/nitrogen blend, to artificially age tire rubber to the chemical
equivalent of 3-4 years in age and, from a chemical aging standpoint,
properties of the skim rubber can be aged just as effectively in an
oven using the 50/50 oxygen/nitrogen blend as on the test wheel, (3)
for oven aging, the wedge rubber ages similar to field-aged tires;
contrasting with tires run to the ``Michelin'' test, which showed
severe reversion in the wedge rubber, (4) tires oven aged with the 50/
50 oxygen/nitrogen blend are in a condition similar to an older full
size spare and, therefore, it may be more appropriate to test the
endurance, high speed, or low pressure performance of a tire aged in
this manner.
Ford also submitted aging testing results, as well as data
regarding the high speed, endurance and low-pressure test. Ford's data
have been granted confidential status. Therefore, it is not available
for review in the docket. Their recommendations from their high-speed,
endurance and low-pressure testing are summarized in the comment
summary section of this document.
4. Goodyear Endurance Testing
In a August 2002 presentation to NHTSA and submission to the
docket, Goodyear provided the following comments on NHTSA's proposed
endurance test based on additional testing conducted by Goodyear: (1)
Heat induced damage mode (tread chunking) exhibited in proposed FMVSS
No. 139 endurance testing is not representative of real world failures
in the field, (2) tires with proven safe field performance will not
pass the proposed FMVSS No. 139 due to tread chunking caused by
excessive heat build-up due to high speed on curved surface and high
load conditions, and (3) tire design changes/compromises to reduce heat
induced tread chunking will negatively impact other safety performance
characteristics (e.g., wet traction, wet handling, dry traction).
Based on the aforementioned observations, Goodyear concluded that
(1) FMVSS No. 139 on a 1.7m curved surface causes shorter footprint
length, high footprint pressures and elevated strain energy resulting
in higher tire running temperatures, (2) 65 mph with a 10% load
reduction on a 1.7m test wheel yields tire temperatures equivalent to
FMVSS No. 139 conditions on a flat surface, (3) a tire that did not
pass the FMVSS No. 139 test on a 1.7m test wheel due to tread chunking
passed when the test was duplicated on a flat surface.
Goodyear stated that it agrees with the agency the test speed needs
to be 75 mph on a flat surface but suggests the following revision to
the proposal to correlate the speed to an equivalent speed and load on
a 1.7m curved surface: (1) Reduce the load by 10% to 100% at the final
load step to effect a 8[deg] F (4.4[deg] C) reduction in the shoulder
surface temperature, and (2) reduce the speed 10 mph, to 65 mph, to
effect an 9[deg] F (5[deg] C) reduction in shoulder surface
temperature. According to Goodyear, the reduced load and speed
parameters would reduce heat induced chunking.
V. Summary of Public Comments on NPRM
NHTSA received over 5,000 comments on the March 2002 NPRM. The
comments were submitted by: vehicle and tire manufacturers and
associations, consumer advocacy organizations and individual members of
the public. Substantive comments are summarized below.
A. NHTSA's Proposed Test Procedures
1. High Speed Test
RMA agreed with NHTSA's proposed conditions for passenger tires but
believed that adjustments in speed and inflation pressure are necessary
for light truck tires to achieve a similar degree of severity as
proposed for passenger tires.
ITRA supported the proposal made by the RMA and stated that NHTSA's
proposed high speed tests results generally show heat precipitated
tread
[[Page 38126]]
chunking as opposed to tread separation.
GRRF, JATMA, and ETRTO urged the Agency to adopt the high speed
test program as specified in the draft Global Technical Regulation
(GTR) submitted to the Agency by the ad-hoc group of WP29/GRRF.
Ford agreed with the agency's position that the current high speed
test procedure should be upgraded.
Advocates supported the agency's selection of test speed
increments, ambient temperature, inflation pressure, load, and duration
with regard to NHTSA's proposed single minimum requirement to be met by
all tires.
CU recommended all tires be speed rated and then tested according
to the RMA 2000 procedure because the RMA 2000 procedure follows GTS
2000 closely and would provide greater promise for reaching global
harmonization than the proposed FMVSS No. 139 test. CU, however,
believed that ambient temperature testing conditions, as specified by
RMA 2000, should be raised to 40[deg] C to equal typical daytime
temperatures in the southern regions of the U.S. during the summer.
RMA, ETRTO, GRRF, and JATMA stated that the temperature increase
from 38[deg] C to 40[deg] C will create considerable complexity to the
industry since most other tests are run at 38[deg] C and suggest
retaining 38[deg] C as the ambient temperature for all tests. PC
supported the agency's modification of the temperature parameters in
order to better simulate real world conditions.
Ford recommended that the test be conducted at the maximum rated
load (105% of the maximum rated load) for the tire and not the 85%
condition so that tires would be tested at loads consistent with the
critical stress conditions for the tire. GRRF stated that the load
percentage used for testing should reflect the vehicle normal load
condition but also take into account the effect of the curvature of the
test drum. ITRA/TANA commended NHTSA for reducing the load in the
parameters of the high speed test from 88% to 85%. CU supported the
change in load if the proposed high speed methodology is adopted and
stated that it will be beneficial for LT tires to be testing with same
load conditions so that light trucks would also have the same reserve
load under normal loading conditions.
GRRF stated that testing on a drum at the lower inflation pressures
specified in the NPRM will result in an increase in stress in areas of
the tire not usually subject to such high stress levels and may result
in some tires having to be ``stiffened'' by having a greater amount of
material in these areas simply to pass the test. RMA stated that the
proposal results in more overload (or over-deflection) in light truck
tires compared to passenger tires and suggested the following test
pressures: LT load range C: 330 kPa; LT load range D: 425 kPa; LT load
range E: 520 kPa. Ford suggested testing at various inflation pressures
to reflect a wider range of conditions to which tires may be exposed:
P-metric 35, 32, 29 psi (241, 220, 200 kPa), Extra Load P-metric 42,
38, 34 psi (290, 262, 234 kPa), LT load range C 50, 46, 42 psi (345,
317, 290 kPa), LT load range D 65, 60, 55 psi (448, 414, 379 kPa), LT
load Range E 80, 73, 66 psi (552, 503, 455 kPa). Public Citizen
supported the proposed inflation pressures for the high-speed test.
GRRF, Ford, RMA, PC, and Advocates believed the test should be
replaced with a procedure based on the rated speed capability of the
tire. They felt that the road safety interests of the consumer would be
better met by using speed values during the high speed test that take
into account the speed capability of the tire and the designed maximum
speed of the vehicle to which it may be fitted. In lieu of a speed-
rating regime, RMA suggested speed steps of 130/140/150 km/h for light
truck tires stating the change in predicted running temperature from a
flat surface to a 1.7-m test wheel is different for passenger and light
truck tires and, therefore, a reduction of 10 km/h in the test speeds
for light truck tires to compensate for this effect and maintain a
change in severity from flat to test wheel similar to passenger tires
is needed.
GRRF stated that a test duration step of 10 minutes has been found
to be acceptable in achieving temperature equilibrium and that the
intermediate speed step duration is less relevant than the duration at
the chosen final speed. CU agreed with NHTSA that the ten-minute speed
steps used in RMA 2000 are too short to evaluate high-speed capability.
2. Endurance Test
ETRTO and GRRF stated that failure mode reached during the test
might not reflect real world tire failure mode because of the
deflection of the tire on the test wheel.
RMA and ITRA/TANA suggested an alternative test protocol that: (1)
Reduces load from 110 to 100%; (2) reduces duration from 40 to 34 hours
in 4/6/24-hour steps; (3) adjusts light truck tire inflation pressure
from 75% of maximum to 81.8% of maximum to reflect a proportional load
capacity as shown in the TRA light truck load tables; (4) adjusts light
truck tire speed from 120 km/h to 110 km/h to maintain comparable
severity from flat to test wheel similar to passenger tires; and, (5)
reduces ambient temperature from 40[deg] C to 38[deg] C. RMA stated
that for light truck tires, this alternative test proposal adjusts the
test conditions to be more equivalent to the tire temperatures that
would be produced on a flat surface for the specified test conditions.
GRRF suggested that consideration should be given to combining the
proposed endurance and aging tests in order to eliminate unnecessary
testing.
CU and Advocates supported the proposed parameters.
GRRF, RMA, and JATMA stated that the test ambient temperature
should be 38 +/- 3[deg] C so the existing equipments can be used
without any change. Advocates agreed with the agency that 40[deg] C is
a more realistic selection based on the ambient operating temperatures
in the southern part of the U.S. and Public Citizen supported the
agency's modification of the temperature parameters in order to better
simulate real world conditions.
RMA suggested testing at 85/90/100 percent of maximum load for P-
metric and light truck tires and argue that the tires in the proposed
test are significantly over-deflected (40 to 36%) during the last load/
time step of 22 hours. Advocates stated that given the excessive
loading of larger light trucks, those usually having GVWR greater than
6,000 pounds, it supports the more demanding alternative discussed by
NHTSA. PC stated that NHTSA should adopt load specifications of 100,
110 and 115 percent to adequately provide for the loading conditions of
these heavier commercial vehicles over 6,000 GVWR.
RMA suggested an adjustment in inflation pressure for LT tires from
75% to 81.8%, following the respective load/pressure formulas for
passenger and light truck tires as defined by the TRA. According to
RMA, this reflects a load capacity difference between passenger and
light truck tires at the same percent pressure. ITRA/TANA stated that
LT tires with heavier casing construction should be tested at pressures
not less than 80 percent of their maximum inflation pressure because
their designs generate a much higher temperature than P-metric tires
when conducted on a curved test wheel in a lab instead of a flat road
surface. Advocates supported the inflation parameters.
RMA believed that the increase in speed is the most significant
change to the endurance test and states that the speed increase from 80
to 120 km/h
[[Page 38127]]
produces an average increase of 30[deg] C in tire temperatures for P-
metric tires over FMVSS No. 109 and an average increase of 40[deg] C
for LT tires. RMA suggested a reduction of 10 km/h for the LT tire test
speed in order to maintain the same relative severity from flat to test
wheel as that which occurs with passenger tires. Ford stated that
increasing the test speed from 50 mph (80 km/h) to 75 mph (120 km/h)
causes reversion in the tire and is not representative of real world
tire performance.
Ford suggested that the agency adopt the current endurance test
protocols as defined in FMVSS No. 109 for a period of 48 hours at the
end of the current protocol and that FMVSS No. 119 be modified to
include an additional test step at 130% rated load. Ford stated that
their data indicate that tires with marginal sidewall designs will have
difficulty passing this added test step. Advocates and PC supported the
40 hours duration as being a sufficiently stringent test.
3. Low Inflation Pressure Performance
a. Generally
GRRF, ETRTO, the Alliance, and JATMA asserted that the proposed
endurance and high-speed tests obviate the need for a low inflation
pressure test.
GRRF, JATMA, ETRTO, and ITRA/TANA opposed to the establishment of
140 kPa as an acceptable level of inflation pressure at which to carry
out a low inflation pressure test. GRRF stated that the use of
inflation pressures as low as 140 kPa (20 psi) for the proposed low
pressure test, taking into account the drum and the duration of the
test, will result in testing at abuse levels well outside any that
could be reasonably expected to be taken into account in tire design
and are outside operating recommendations given by the tire industry.
RMA stated that the low-pressure test should be run at 90% of the
tire's maximum load capacity rather than 100% so that 20 psi is not 42%
below the required test load but at 30%, the maximum allowed under the
TPMS final rule.
The Alliance and Ford stated the low-pressure testing protocols,
proposed in the notice, are not representative of real world aging
conditions because the 40-hour endurance test preceding the low-
pressure tests causes the belt region to age anaerobically. Results
from these tests showed a tremendous heat build up in the tire which
leads to tread chunking, a benign failure mode rarely if ever seen
outside of a racetrack. They stated that it would be better to run a
low-pressure test on a tire that had gone through an aging procedure
that correlates to actual field aging of tires.
CU stated that the NPRM does not provide enough information to
determine when exactly the tire would be run to the low-pressure
conditions following successful completion of the endurance test. They
recommended that the tire be allowed to cool down for a minimum of
three hours at the ambient test condition before starting the low-
pressure test.
b. Low Inflation Endurance
RMA, ITRA and TANA favored Option 1 stating that the Option 2
conditions are so severe that the tires experience thermal runaway
(i.e., the temperature did not stabilize within 30 minutes) during the
required steps. RMA recommended a modified Option 1 test with adjusted
test conditions which they state more accurately reflect performance on
the flat surface and to more closely reflect the conditions that should
exist when the TPMS warning is given: (1) Lowers LT tire speed from 120
to 110 km/h to maintain consistency with the RMA proposed endurance
test conditions; (2) reduces the test load from 100 to 90% of the
tire's maximum load capacity to reasonably simulate the effect of a 30%
decrease in inflation pressure when the test pressure is specified at
the minimum pressure listed in the NPRM at paragraph S6.4.1.1.1; and,
(3) extends the time from 15 minutes to one hour for post-test
measurement of inflation pressure.
CU favored an endurance type TPMS low pressure test over the high
speed version proposed because they believe it is more representative
of conditions consumers are likely to encounter. However, CU believed
that testing the tires for 90 minutes at 75 mph represents too short a
distance (just 112.5 miles) and is well below the typical fuel range of
most vehicles. CU recommends that the test duration be at least four
hours at 75 mph, simulating a distance of 300 miles and is more
representative of the fuel range of a typical vehicle.
Advocates regarded this alternative as undemanding and insufficient
for determining the underinflation tolerance of current light vehicle
tires. Public Citizens believed that the stringency of the test is
highly questionable considering that all of the tires tested passed the
test.
c. Low Inflation High Speed
GRRF noted surprise that a test load of only 67% is quoted because
it seems impractical for a consumer to reduce the vehicle load
following a TPMS warning indication.
JATMA stated that this test is unjustified to demand tire
performance of this type because consumers would not continue driving
at above 140 km/h for over one hour with a tire pressure warning.
Ford supported the low-pressure high-speed test if the tires are
aged in an oven with a 50/50 blend of oxygen and nitrogen and an
allowance is made for a 2-hour break-in period at 180 kPa and 120 km/h
at 85% load, similar to the FMVSS No. 109 high-speed test. Ford stated
that the aging process and test protocol more closely approximates a
full size spare that is put into service after 3-4 years: oxidatively
aged and potentially under-inflated. The break-in period would give the
aged tire an opportunity to be worked before being deflated and run to
the low pressure test procedure and does not cause reversion in wedge
rubber of the tire.
Advocates and PC supported the parameters of this test. However,
Advocates regarded a 67 percent load as completely unrealistic and
recommends that the agency consider raising the loading percentage for
the low pressure/high speed test from 67 percent to 100 or 110 percent.
4. Road Hazard Impact
RMA stated the current FMVSS No. 109 plunger test should remain
only for bias ply tires because radial tires are not susceptible to the
type of failure that the current plunger tests was designed to prevent.
RMA, GM, the Alliance, ETRTO, and GRRF stated that the SAE J1981
test was developed as a wheel damage test, to test a wheels ability to
withstand potholes and other anomalies, and has very limited use or
experience within the industry as a tire test and significant work will
be required to develop it into a tire test. RMA, ITRA/TANA, JATMA, GM,
Alliance, and Advocates stated that a road hazard test, if NHTSA feels
it is necessary, should be deferred for further study and research and
to not be included in the proposed FMVSS No. 139.
Ford, the Alliance, and CU recommended that the agency retain the
current test and Ford and CU suggest that the agency augment the
stringency of the test. Ford stated that it currently uses twice the
value specified in FMVSS No. 109 as a corporate specification for their
tire suppliers and this level provides a reasonable indication that
radial tires will exhibit good resistance to rock inducted tread
damage.
[[Page 38128]]
Advocates, PC, and CU stated that NHTSA needs to explore other
methods using more sophisticated means of evaluation, e.g.,
shearography, for damage. GM noted that any anomaly from the pendulum
impacts in its testing was undetectable by visual inspection.
5. Bead Unseating
RMA and GRRF believed that a bead-unseating test is unnecessary for
radial tires. RMA, and ITRA/TANA suggested that if a bead unseating
test must be maintained, then the current test be retained rather than
adopting a completely new test. However, they believed that it does
need to be modified to take into account the aspect ratio of tires.
ITRA and TANA asked that retread tires be exempt from the proposed
tests because the bead of the tire is part of the original casing and
is not altered in the retreading process, and, as such, there would be
redundancy in testing the original casings.
GRRF, Toyota, the Alliance, CU, and Ford stated that the
introduction of this revised test without further validation would seem
to be premature at this stage. They asserted concerns regarding the
lack of a fully defined procedure, the specification of the test
equipment, the costs of equipment, and the availability of suitable
equipment on the open market. Several commenters, including Toyota,
Ford, and the Alliance, asserted that there are significant differences
between the agency's proposal and Toyota's test and/or certain
specifications that need refinement, such as the load values,
specifications for the test wheel/rim, inflation pressures, test device
methods, and lateral force.
PC and Advocates supported the agency's proposal for the air loss
bench test method because the test is independent of vehicle type but
do not support the 200 millimeters per second as being satisfactory
because they say it reveals nothing about how a tire would perform in a
skid when the vehicle encounters either a pothole or a raised fixed
object on the roadside applying an extremely rapid lateral, peak load
to the tire. Advocates, however, questioned whether the test advances
tire safety if all current production tires would pass the test.
6. Aging Effects
a. Generally
RMA and ITRA/TANA stated that none of the options in the NPRM are
accepted industry tests with a proven relationship to actual tire
performance. RMA and GRRF added that any aging test would be redundant
in light of the revised high-speed and endurance tests plus a new low-
pressure test.
The Alliance and ETRTO stated that the three test options proposed
artificially decay of the materials in the tire structure, but those
decays do not reflect what occurs in ``real life'' over a long period
of service.
Ford stated that the predominant factor for tire aging in normal
service is aerobic/oxidative aging, which may be accelerated by heat
and cites to the NHTSA Office of Defects Investigation (ODI)
Engineering Analysis Report on Firestone tires in support of this
statement. Ford and the Alliance stated that the proposed tests do not
appear to age the tire aerobically/oxidatively. Ford recommended aging
mounted tires with a 50/50 blend of oxygen/nitrogen in an oven 70[deg]
C for 2 weeks. After this oven aging, they recommend a peel test be
performed on the tire and suggest that it may be more appropriate to
test the endurance, high speed, or low-pressure performance of a tire
aged in this manner.
ITRA/TANA argued that retreads should be exempt from this test.
PC and Advocates asserted that shearographic analysis is critical
in accurately determining aging test compliance.
Consumers Union believed further investigation of a more suitable
procedure is needed.
b. Adhesion (Peel) Test
RMA stated that the proposed adhesion peel force test is the least
appropriate option due to the following reasons: (1) ASTM-D413 is a
peel adhesion test used in the industry to monitor trends and detect
large shifts in historic levels and, under the best scenario for
minimizing variability, has a 16.8% inherent variability, (2) the test
is evaluating only a component of the tire, not the tire's overall
performance, (3) peel force does not correlate with field performance,
or, at a minimum, a recognized industry test wheel test--the peel
adhesion test is not a separation-initiating test, it relates only to
propagation (4) there is a lack of mechanical and chemical interaction
as would occur in actual field.
GRRF and JATMA opposed this test stating that the proposals do not
specify which of the several interfaces of the belt construction are to
be tested.
ETRTO stated that the ASTM method is known by the industry to
evaluate the vulcanized cord ply, not cut specimens from the tire.
CU believed that the peel test is not sufficiently repeatable or
precise and urged NHTSA to conduct more research to develop a practical
and efficient method of testing the effects of tire aging.
c. Michelin's Long Term Durability
RMA, JATMA, GRRF, and CU did not support this test because of its
length and inherent cost.
ETRTO and JATMA stated that the use of pure oxygen for inflating
tires, presents a danger of explosion and requires special safety
procedures to be implemented in the laboratories.
JATMA stated that the test ambient temperature should be 38 +/-
3[deg] C so existing equipments can be used without any change. JATMA
also states that the NHTSA test criterion that no reduction of
inflation pressure from initial test pressure is not possible because
O2 is consumed during the test.
PC supported this test as a starting point for the proposed aging
test.
d. Oven Aging
ETRTO asserted that this test will cause an extended vulcanization
of all rubber components inside a tire and does not represent ``real
world'' service conditions where the area subjected to heating and to
repeated stresses is that inside the edges of the tread area.
RMA, ITRA/TANA, and GRRF believed this test is a more valid measure
of tire performance than Option 1 and significantly less onerous than
Option 2. RMA recommended the following modifications if the agency
chooses to pursue this test: (1) lower the aging temperature from 75 to
70[deg] C. 70[deg] C is an industry standard for aging of rubber
compounds and used by some companies for aging of tires prior to test,
and (2) adopt the ambient temperature, inflation pressures, and speed
from the RMA recommended endurance tests with steps of: (a) 4 hours at
85% load, (b) 6 hours at 90% load, (c) 14 hours at 100% load.
JATMA stated that a 15-day test is not suitable for mass production
management. JATMA further states that the test ambient temperature
should be 38 +/- 3[deg] C so the existing equipments can be used
without any change.
CU stated that this procedure does not resemble what consumers
experience in the real world with tire aging. In real world conditions,
tires do not heat up evenly, and it is often the hot spots and dynamic
flexing that define the weak link in tire design.
B. Application of New Standard/Deletion of FMVSS No. 109
RMA and TRA recommended that the proposed FMVSS No. 139 apply to
new pneumatic radial tires on powered
[[Page 38129]]
motor vehicles (other than motorcycles) that have a gross vehicle
weight rating (GVWR) of 10,000 pounds or less and that were
manufactured after 1975 and that tires designed for severe snow
conditions, speed restricted tires, various trailer tires for special
use, temporary service spare tires, and all bias tires should be
excluded from FMVSS No. 139 and continue to be certified under existing
FMVSS Nos. 109 and 119. RMA suggests that, under FMVSS No. 139, a
passenger tire should be defined as one intended for normal highway
service and its size designation typically shown as ``P'' metric or
``Hard'' metric and a light truck tire should be defined as one
intended for normal highway service and its size designation includes
``LT'' and is load range ``C'', ``D'', or ``E''. JATMA requests that
performance requirements for deep tread depth snow tires be stipulated
apart from FMVSS No. 139 because of their special usage and design
characteristics, e.g., deep grooved tread.
JATMA and GRRF stated that the tire size designation, in addition
to the load range, should be clearly stipulated for LT tires. GRRF
stated that depending on tire size, some high load capacity LT tires
correspond to a gross vehicle mass greater than 10,000 lbs.
SEMA, ITRA/TANA, Denman and Specialty Tires requested that limited-
production specialty radial and bias-ply tires remain subject to the
current testing procedures of FMVSS Nos. 109 and 119 because (1) tires
manufactured in limited production do not present a general safety
issue; (2) limited production specialty bias-ply tires cannot meet the
standard of proposed FMVSS No. 139 and will be unfairly outlawed; (3)
the potential cost for small businesses to otherwise comply with these
rules would not be justified; and (4) NHTSA testing procedures and
requirements result from the testing and analysis of solely radial
tires.
C. Modification of Application of FMVSS Nos. 110 and 120
AIAM believed that NHTSA inadvertently proposed a prohibition on
the use of Load Range E tires on vehicles exceeding 10,000 lbs. GVWR
by, in S5.1.1 of FMVSS 120, requiring each vehicle to be equipped with
tires complying with FMVSS No. 119. AIAM recommends that NHTSA revise
S5.1.1 of FMVSS 120 to permit the installation of tires meeting the
requirements set forth in FMVSS No. 139 and the rims listed in
accordance with FMVSS No. 139 on vehicles exceeding 10,000 lbs. GVWR,
as long as the tire load rating is not exceeded.
D. Modification to FMVSS Nos. 117 and 129
ITRA/TANA recommended that retreaded tires not be subjected to the
proposed road hazard and bead unseating tests because the retread
process does not affect the structure of an original casing and it is
redundant to test a casing twice.
GRRF stated that principle of requiring retread tires to meet the
same performance requirements as new tires is followed in the United
Nations ECE Regulations 108 and 109 for car and truck retread tires,
respectively.
E. De-Rating of P-metric Tires/Tire Selection/Load Reserve
RMA and GRRF supported NHTSA's retention of the 1.10 load service
factor used to reduce the load rating of passenger car tires when
installed on an MPV, truck, bus, or trailer, as specified in Part
571.110 Paragraph S4.2.2.2 of the proposed rule. RMA believed that this
reduction in load rating is necessary for the reasons stated by NHTSA
and is also appropriate to reduce the load rating for passenger car
tires used on light trucks, vans, SUVs, and trailers for the following
reasons: (1) higher stress on the tire due to the higher center of
gravity of these vehicles; (2) more severe service conditions as
compared to passenger cars; (3) greater potential for overload due to
open cargo areas and increased likelihood for towing; and (4) more tire
related problems on light trucks, SUVs, and vans.
RMA and GRRF stated that selection based on vehicle normal load not
exceeding 88% of the tire maximum load would reduce the potential for
overloading of tires.
GM recommended that the tire selection criteria not be linked to
the load used in the high-speed test.\21\
---------------------------------------------------------------------------
\21\ The 88% used for the load in the high speed test is
currently linked to the reserve load determination in FMVSS No. 110.
In 1982, the agency stated in a rulemaking (47 FR 36180) that the
88% load on the test road wheel is equivalent to 100% load on a flat
surface.
---------------------------------------------------------------------------
The Alliance, AIAM, Subaru, Honda, and GM strongly recommended that
the tire selection criteria in the proposed standard be modified as
follows: (1) De-rating of the tire load capacity by dividing by 1.10 be
applied only when comparing the GAWR with the vehicle maximum load and
not on the vehicle normal load on tire for passenger car tires used on
MPVs and light trucks; and (2) for vehicle normal load on a tire, even
when passenger car tires are used on MPVs and light trucks, use 88% of
the maximum load rating of the tire as marked on the sidewall. These
vehicle manufacturers asserted that a lack of attention to the
influence on vehicle design could lead to potentially serious
unintended consequences (e.g., increasing tire size beyond the need to
provide adequate load capacity could raise the center of gravity of the
vehicle, which may adversely affect it handling and stability and
increase the likelihood of rollovers in some situations).
Ford agreed with the agency that tire robustness could be increased
through additional load margin in the application or rating of tires.
Ford recommended that the agency require tires to be tested at 105% of
their rated load for all vehicle applications 10,000 lbs. GVWR and
below. They believed that this additional 5% reserve capability at the
maximum rated load condition would provide increased robustness for
tire application on all vehicles, not only in OE applications.
PC and Advocates commended the agency for requiring LT tires to
provide for a reserve load. However, they believe that a 15 percent
load specification does not adequately account for the typical loading
conditions for the range of these vehicles. PC recommends that the
agency require between an 18 and 20 percent reserve load for vehicles
that exceed the 6000 lbs. GVWR. Advocates urged the agency to consider
a reserve figure of 18 percent for all light trucks or, in the
alternative, a reserve figure of 18 percent for those from 6,001 to
10,000 pounds GVWR.
F. Lead Time
RMA, ETRTO, JATMA, and GRRF stated that it would not be possible to
comply with effective dates of September 1, 2003, for passenger car
tires, and September 1, 2004, for light truck tires. RMA added that if
their recommended changes are accepted, the number of modifications
will not be as great and compliance could be accomplished on a more
expedited basis, possibly within five (5) years from the date of the
final rule.
JATMA stated that a 5-year lead time is required in case of tires
supplied to original equipment manufacturers to evaluate and achieve
the target performance for driving stability, riding comfort, and noise
etc. Also, they stated that facilities need to be increased, test
procedure needs to be formed, and employees need to be trained.
The Alliance, GM, Ford, DC, and Mitsubishi recommended that the new
tire performance requirements and the amended vehicle requirements of
FMVSS NO. 110 become optional as soon as the final rule is published,
and become mandatory on September 1, 2007. They requested the longer
lead
[[Page 38130]]
time because of the number of tires that will have to be changed in
terms of materials/compounds or construction, and the time required to
make these changes will have indirect effects on the vehicles which
will require revalidation for braking, dynamics, fuel consumption,
ride, handling, and noise/vibration, including legal noise
requirements. Additionally, the Alliance stated that a tire designed to
the new requirements cannot be mass-produced until it has been matched
to a given vehicle, and the vehicle has been validated for braking,
vehicle dynamics, fuel economy, ride, handling, etc. Therefore, the
tire and vehicle effective dates must be the same.
DC stated that it cannot begin to conduct necessary vehicle
development and tuning programs until an adequate supply of tires
meeting any new regulations become readily available from the tire
manufacturers (in quantities, styles, and sizes sufficient for vehicle
development). They strongly urged that there must be at least a two
year lag time between the sufficient availability of development tires
meeting any new requirements and the vehicle level phase-in or
effective date scheduled.
Advocates urged NHTSA to consider a one-year compliance delay from
the date of a final rule effective on September 1, 2002, and believes
that LT tires need to be improved just as quickly, if not more quickly,
than P-metric tires and a delay in compliance for LT tires is not in
the best interest of vehicle and traffic safety.
G. Shearography Analysis
JATMA stated that shearography is suitable for evaluation of new
compound and new tire structure of developing products, but is too
expensive and not suitable for a test to assure the quality of mass
production goods.
The Alliance, Ford, ETRTO, GRRF, and ITRA/TANA stated that all
shearography analysis techniques rely on a subjective assessment by a
skilled operator and the present state of technology is such that they
may not be acceptable as a regulatory control requirement.
PC supported the use of shearography analysis in conjunction with
visual inspection. Additionally, Public Citizen recommended that the
agency devise a list of all the possible indications of tire failure.
H. Revise UTQG
ETRTO, GRRF, and CU suggested that test requirements for
Temperature in UTQG are useless once the correct service description
including the Speed Symbol is required for the tires, which are then
tested according to the corresponding high-speed test schedules in UN/
ECE Regulations 30 and 54.
RMA urged NHTSA not to revise the existing UTQGS scope and testing
conditions at this time.
I. Additional Questions
1. Opportunity To Harmonize
The Alliance, ETRTO, RMA, the Center for Regulatory Effectiveness
(CRE), and GRRF stated that the adoption of a UN/ECE Regulation 30 type
test, such as the GTS-2000 or proposed GTR, would help to ensure that
safety standards are consistent worldwide and that the burden on
industry through having to meet several differing standards of various
countries is removed. CRE also suggested that NHTSA is obligated to
consider the following voluntary consensus standards--ISO 10191, SAE
J1561, and SAE J1633/ISO 10454 under the National Technology Transfer
and Advancement Act. RMA argued that this action would assist the
breaking down of barriers to trade and improve the acceptability of
USA-produced tires in a global market.
RMA asserted that NHTSA's proposal might constitute a technical
barrier to trade in violation of the WTO Agreement on Technical
Barriers to Trade.
The Alliance stated that, even if the agency considers the current
harmonization proposal unacceptable, the agency should commit to
developing a harmonized proposal.
Advocates stated that NHTSA could use the data and testing
protocols of the optional test for wet grip of tires discussed in the
actions of the World Forum for Harmonization of Vehicle Regulations
(WP.29) Working Party On Brakes and Running Gear (GRRF) as a departure
point for determining how best to establish tire adhesion requirements
to be included in the proposed new Standard No. 139.
2. ``Real-World'' Testing Procedures
ETRTO stated that ``real-world'' testing procedure need to be
pursued by defining accelerated test conditions that reflect the
effective failure mode of the tires in service.
GRRF supported the approach of using controllable, laboratory based
tests wherever possible and provided that they reproduce in-service
conditions.
Ford stated that vehicular testing is not practicable due to
variation in vehicle size and loading and the wide range of wheel/tire
combinations and that the tire standard should continue to be an
equipment standard and that tires should continue to be certified by
tire manufacturers.
3. Vehicle Model Year 1975
GRRF supported the cut-off date of 1975 and suggests that
consideration is given to the retention of FMVSS No. 109 for tires for
earlier vehicles.
4. Required Inflation Pressures
GRRF and ETRTO suggested that all U.S. tires should be marked with
inflation pressures expressed in kPa, as per the internationally
recognized standard units.
RMA stated that inflations pressures of 32, 36, 40 and 60 psi
should be retained in the existing FMVSS No. 109 standard, but should
not be included in the new FMVSS No. 139.
The Alliance and Ford believed the four pressures should be
retained for tire rating and testing.
The Alliance requested that NHTSA remove the current and proposed
requirement to round the psi equivalent of kPa to the next highest
whole number, and to round the pound equivalent of kilogram to the
closest whole number.
J. Other
1. Test Condition Tolerances
RMA suggested that NHTSA adopt the tolerances listed in ASTM-F-551
Standard Practice for Using a 67.23-in. (1.707-m) Diameter Laboratory
Test Wheel in Tire Testing.
2. Tire Pressure Load Reserve Limit
RMA suggested that NHTSA should adopt a specific tire pressure
reserve limit and comments that they will be petitioning the agency for
such a ruling in the near future.
K. Costs \22\
---------------------------------------------------------------------------
\22\ Comments on costs are discussed in greater detail in the
FRE.
---------------------------------------------------------------------------
RMA and ETRTO stated that the agency's estimate that the proposed
standards will impose costs of $282 million on the tire industry is
grossly inaccurate. RMA estimated that the first year costs would
exceed $1.5 billion with a continuing annual cost to comply in excess
of $400 million depending on the options chosen for the final rule.
ITRA stated that the agency's estimates also do not include small
manufacturers and foreign manufacturers that import tires to the U.S,
and retreaders, and that the proposed regulation could result in the
downfall of the retread industry.
[[Page 38131]]
RMA, SEMA, ITRA/TANA, Denman, Hoosier, and Specialty tires stated
that no cost/benefit analysis has been undertaken for limited
production bias-ply and radial specialty aftermarket tires and the new
testing requirements associated with NHTSA's proposed FMVSS No. 139
will jeopardize the specialty aftermarket tire industry unless special
dispensation is made for these manufacturers. SEMA stated that at least
three separate specialty tire manufacturers, Denman, Specialty Tires,
and Hoosier are small businesses employing less than 1,000 people.
GM and the Alliance stated that NHTSA has not considered the
potential influence of changes to the tire on the performance of the
vehicle and that vehicle modifications of significant magnitude would
cost the industry substantial amounts in investment and unit costs per
vehicle.
L. Benefits \23\
---------------------------------------------------------------------------
\23\ Comments on benefits are discussed in greater detail in the
FRE.
---------------------------------------------------------------------------
GRRF asserted that the analysis of benefits appears to be
incorrectly based on the assumption that the problems recently
experienced have been caused primarily by incorrect design rather than
by difficulties in manufacture, improper application, general poor
maintenance or abuse during service.
The Alliance stated that the basis for the estimated benefits is
unsubstantiated because of the lack of specific information on the
causes of tire failures and because of the agency's inability to
estimate what proportion of tires would need improvement and by what
amount.
Advocates argued that there is little doubt that a reduction in
tire failure rates would result in fewer blowouts and, therefore, fewer
rollover crashes. They also asserted that tire failures and their role
in crashes are severely underreported and, therefore, that the benefits
are much greater than the agency is able to quantify. Advocates agreed
with the agency that the benefits of stronger standards ensuring
greater speed and heat tolerance for both P-metric and LT tires are
intuitively apparent even though it is typically more difficult to
quantify benefits for crash avoidance rulemaking proposals than for
crashworthiness proposals.
PC argued that the resulting societal costs (e.g., loss of
workplace productivity, fatalities, medical costs, property damage
costs and costs of travel delay on congested roadways) of motor vehicle
crashes must be considered when estimating the benefits of a proposed
regulation and that reducing the variability of tires could yield
benefits from the proposed tests.
VI. Agency Decision Regarding Final Rule
A. Summary of Final Rule and Rationale
The agency is establishing a single standard for light vehicle
tires, FMVSS No. 139, New Pneumatic Radial Tires for Light Vehicles.
Under this standard, light vehicle tires are required to meet a high-
speed test, an endurance test, a low inflation pressure performance
test, a resistance-to-bead unseating test, and a road hazard impact/
strength test. The standard applies to tires for passenger cars,
multipurpose passenger vehicles, trucks, buses and trailers with a
gross vehicle weight rating (GVWR) of 4,536 kilograms (10,000 pounds)
or less, manufactured after 1975.\24\ The following chart compares the
types of test requirements that currently exist, those that have been
suggested by third parties, and those are being established by this
agency:
---------------------------------------------------------------------------
\24\ This final rule is applicable to LT tires up to load range
E. This load range is typically used on large SUVs, vans, and
trucks.
Table 1.--Comparison of Types of Tire Performance Requirements in Various Existing and Draft Tire Standards
--------------------------------------------------------------------------------------------------------------------------------------------------------
FMVSS 119 GRRF draft FMVSS No. 139
Tests FMVSS 109 [dagger][dagger] GTR GTS-2000 RMA 2000 ECE R30 (As adopted)
--------------------------------------------------------------------------------------------------------------------------------------------------------
High Speed................................... X ................ X[hairsp] X X X X
[dagger]
Endurance.................................... X X X[hairsp] * X[hairsp] ** X ............ X
Low pressure performance..................... ............ ................ ............ ............ ............ ............ X
Strength; or Road Hazard Impact.............. X X ............ ............ ............ ............ X
Bead Unseating............................... X ................ X[hairsp] ............ ............ ............ X
***
Accelerated Aging............................ ............ ................ ............ ............ ............ ............ .................
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Endurance test for radial tires rated ``Q'' and below. Identical testing parameters as FMVSS No. 109 Endurance Test.
** Endurance test for radial tires rated ``Q'' and below.
*** Identical testing parameters as FMVSS No. 109 bead unseating test.
[dagger] Testing parameters had not been agreed upon by the ad hoc working group.
[dagger][dagger] For LT tires only.
Both the high speed test and the endurance test specify testing
parameters (ambient temperature, load, inflation pressure, speed, and
duration) that make the tests more stringent than those tests currently
found in FMVSS Nos. 109 and 119, as well as the tests suggested by
industry. Most significantly, the proposed high speed test specifies
test speeds (140, 150 and 160 km/h (87, 93, and 99 mph)) substantially
higher than those specified in FMVSS No. 109 (120, 128, 136 km/h (75,
80, 85 mph)). Likewise, the endurance test specifies a test speed 50%
higher (120 km/h (75 mph)) than that currently specified in FMVSS No.
109 (80km/h (50 mph)), as well as a duration 2 hours longer (24 hours)
in the final load step than that proposed in the NPRM (22 hours). At
the specified test speed (120 km/h), the endurance test mileage (2,550
miles) is 50% longer than the mileage that a tire endures under the
current endurance test (1,700 miles).
The final rule also adopts a low inflation pressure performance
test that seeks to ensure a minimum level of performance safety in
tires when they are underinflated to 140 kPa (20 psi).
Instead of replacing the current strength test in FMVSS No. 109,
the agency is retaining that test for passenger cars and retaining the
strength test in FMVSS No. 119 for LT tires. Agency testing data and
public comments called into question whether the test proposed in the
NPRM, a road hazard impact test that is modeled after a SAE recommended
practice, is both more stringent than the FMVSS No. 109 ``plunger
test'' and correlates well with actual field performance. The FMVSS
[[Page 38132]]
Nos. 109 and 119 strength tests will remain until the agency completes
its research on road hazard impact and decides whether to initiate
rulemaking to adopt a new or revised test.
The