[Federal Register: June 5, 2002 (Volume 67, Number 108)]
[Rules and Regulations]
[Page 38703-38749]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr05jn02-9]
[[Page 38703]]
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Part II
Department of Transportation
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National Highway and Traffic Safety Administration
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49 CFR Parts 571 and 590
Federal Motor Vehicle Safety Standards; Tire Pressure Monitoring
Systems; Controls and Displays; Final Rule
[[Page 38704]]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Parts 571 and 590
[Docket No. NHTSA 2000-8572]
RIN 2127-AI33
Federal Motor Vehicle Safety Standards; Tire Pressure Monitoring
Systems; Controls and Displays
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation (DOT).
ACTION: Final rule.
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SUMMARY: In response to a mandate in the Transportation Recall
Enhancement, Accountability, and Documentation (TREAD) Act of 2000,
this agency is issuing a two-part final rule.
The first part is contained in this document. It establishes a new
Federal Motor Vehicle Safety Standard that requires the installation of
tire pressure monitoring systems (TPMSs) that warn the driver when a
tire is significantly under-inflated. The standard applies to passenger
cars, trucks, multipurpose passenger vehicles, and buses with a gross
vehicle weight rating of 10,000 pounds or less, except those vehicles
with dual wheels on an axle.
This document establishes two compliance options for the short-
term, for the period between November 1, 2003, and October 31, 2006.
Under the first compliance option, a vehicle's TPMS must warn the
driver when the pressure in any single tire or in each tire in any
combination of tires, up to a total of four tires, has fallen to 25
percent or more below the vehicle manufacturer's recommended cold
inflation pressure for the tires, or a minimum level of pressure
specified in the standard, whichever pressure is higher. Under the
second compliance option, a vehicle's TPMS must warn the driver when
the pressure in any single tire has fallen to 30 percent or more below
the vehicle manufacturer's recommended cold inflation pressure for the
tires, or a minimum level of pressure specified in the standard,
whichever pressure is higher. Compliance with the options would be
phased in during that period by increasing percentages of production.
The second part of this final rule will be issued by March 1, 2005,
and will establish performance requirements for the long-term, i.e.,
for the period beginning on November 1, 2006. In the meantime, the
agency will leave the rulemaking docket open for the submission of new
data and analyses concerning the performance of TPMSs. The agency also
will conduct a study comparing the tire pressures of vehicles without
any TPMS to the pressures of vehicles with TPMSs, especially TPMSs that
do not comply with the four-tire, 25 percent compliance option.
Based on the record now before the agency, NHTSA tentatively
believes that the four-tire, 25 percent option would best meet the
mandate in the TREAD Act. However, it is possible that the agency may
obtain or receive new information that is sufficient to justify a
continuation of the options established by this first part of this
rule, or the adoption of some other alternative.
DATES: This final rule is effective August 5, 2002. Under the rule,
vehicles will be required to comply with the requirements of the
standard according to a phase-in beginning on November 1, 2003. If you
wish to submit a petition for reconsideration of this rule, your
petition must be received by July 22, 2002.
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 other non-legal
issues, you may call Mr. George Soodoo or Mr. Joseph Scott, Office of
Crash Avoidance Standards (Telephone: 202-366-2720) (Fax: 202-366-
4329).
For legal issues, you may call Mr. Dion Casey, Office of Chief
Counsel (Telephone: 202-366-2992) (Fax: 202-366-3820).
You may send mail to these officials at National Highway Traffic
Safety Administration, 400 Seventh Street, SW, Washington, DC 20590.
You may call Docket Management at 202-366-9324. You may visit the
Docket on the plaza level at 400 Seventh Street, SW, Washington, DC,
from 10:00 a.m. to 5:00 p.m., Monday through Friday.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Executive Summary
A. Highlights of the Notice of Proposed Rulemaking
B. Highlights of the Preliminary Determination About the Final
Rule
C. OMB Return Letter
D. Highlights of the Final Rule
1. Part One--Phase-in (November 2003 through October 2006)
2. Part Two--November 2006 and Thereafter
E. Summary Comparison of the Preliminary Determination and the
Final Rule
II. Background
A. The Transportation Recall Enhancement, Accountability, and
Documentation Act
B. Previous Rulemaking on Tire Pressure Monitoring Systems
C. Summary of the Notice of Proposed Rulemaking
D. Summary of Public Comments on Notice
1. Vehicles Covered
2. Phase-In Options and Long-Term Requirements
a. Definition of ``Significantly Under-Inflated''
b. Number of Tires Monitored
3. Lead Time
4. Reliability
5. Costs and Benefits Estimates
E. Submission of Draft Final Rule to OMB
F. OMB Return Letter
G. Public Comments on OMB's Return Letter
H. Congressional Hearing
III. Safety Problem
A. Infrequent Driver Monitoring of Tire Pressure
B. Loss of Tire Pressure Due to Natural and Other Causes
C. Percentage of Motor Vehicles with Under-Inflated Tires
D. Consequences of Under-Inflation of Tires
1. Reduced Vehicle Safety--Tire Failures and Increases in
Stopping Distance
2. Reduced Tread Life
3. Reduced Fuel Economy
IV. Tire Pressure Monitoring Systems
A. Indirect TPMSs
B. Direct TPMSs
C. Hybrid TPMSs
V. Summary of Preliminary Determination About the Final Rule
A. Alternative Long-Term Requirements Analyzed in Making
Preliminary Determination
B. Phase-In and Long-Term Requirements
VI. Response to Issues Raised in OMB Return Letter About Preliminary
Determination
A. Criteria for Selecting the Long-Term Requirement
1. Tire Safety and Overall Vehicle Safety
2. Statutory Mandate
B. Relative Ability of Direct and Current Indirect TPMSs to
Detect Under-Inflation
C. Analysis of a Fourth Alternative Long-Term Requirement: One-
Tire, 30 Percent Under-Inflation Detection
D. Impact of One-Tire, 30 Percent Alternative on Installation
Rate of ABS
E. Overall Safety Effects of ABS
F. Technical Foundation for NHTSA's Safety Benefit Analyses
VII. The Final Rule
A. Decision to Issue Two-Part Final Rule
B. Part One of the Final Rule--November 2003 through October
2006
1. Summary
2. Congressional Intent
3. Vehicles Covered
4. Phase-In Options and Requirements
a. Alternatives Considered
i. Threshold Level of Under-Inflation
ii. Number of Tires Monitored
b. Option One: Four Tires, 25 Percent Under-Inflation
c. Option Two: One Tire, 30 Percent Under-Inflation
[[Page 38705]]
d. Special Written Instructions for Option Two TPMSs
5. Other Requirements
a. Time Frame for Telltale Illumination
b. Duration of Warning
c. Temporary Disablement
d. System Calibration
e. Replacement Tires
f. Monitoring of Spare Tire
g. Temperature Compensation
h. Low Tire Pressure Warning Telltale
i. Color
ii. Symbol
iii. Self-Check
i. General Written Instructions for All TPMSs
j. Test Conditions
k. Test Procedures
6. Lead Time
C. Study of Effects of TPMSs That Do Not Meet a Four-Tire, 25
Percent Under-Inflation Requirement
1. Effect on Tire Pressure
2. Effect on Number of Significantly Under-Inflated Tires
D. Part Two of the Final Rule--November 2006 and Thereafter
VIII. Benefits
A. Tire Safety Benefits
1. Skidding/Loss of Control
2. Stopping Distance
3. Flat Tires and Blowouts
4. Unquantified Benefits
B. Non-Tire Safety Benefits
C. Total Quantified Safety Benefits
D. Economic Benefits
1. Fuel Economy
2. Tread Life
IX. Costs
A. Indirect TPMSs
B. Direct TPMSs
C. Hybrid TPMSs
D. Vehicle Cost
E. Maintenance Costs
F. Testing Costs
G. Unquantified Costs
H. ABS Costs
I. Net Costs and Costs Per Equivalent Life Saved
X. Rulemaking Analyses and Notices
I. Executive Summary
A. Highlights of the Notice of Proposed Rulemaking
NHTSA initiated this rulemaking with the publication of a Notice of
Proposed Rulemaking (NPRM)(66 FR 38982, Docket No. NHTSA-2000-8572) on
July 26, 2001. The NPRM proposed to require passenger cars, light
trucks, multipurpose passenger vehicles, and buses with a gross vehicle
weight rating of 10,000 pounds or less, except those vehicles with dual
wheels on an axle, to be equipped with a tire pressure monitoring
system (TPMS).
The agency sought comment on two alternative sets of performance
requirements for TPMSs and proposed adopting one of them in the final
rule. The first alternative would have required that the driver be
warned when the pressure in any single tire or in each tire in any
combination of tires, up to a total of four tires, had fallen to 20
percent or more below the vehicle manufacturer's recommended cold
inflation pressure for the vehicle's tires (the placard pressure), or a
minimum level of pressure specified in the standard, whichever was
higher. (This alternative is referred to below as the four-tire, 20
percent alternative.) The second alternative would have required that
the driver be warned when the pressure in any single tire or in each
tire in any combination of tires, up to a total of three tires, had
fallen to 25 percent or more below the placard pressure, or a minimum
level of pressure specified in the standard, whichever was higher.
(This alternative is referred to below as the three-tire, 25 percent
alternative.) The minimum levels of pressure were the same in both
proposed alternatives. The adoption of four-tire, 20 percent
alternative would have required that drivers be warned of under-
inflation sooner and in a greater array of circumstances. It would also
have narrowed the range of technologies that manufacturers could use to
comply with the new standard.
There are two types of TPMSs currently available, direct TPMSs and
indirect TPMSs. Direct TPMSs have a tire pressure sensor in each tire.
The sensors transmit pressure information to a receiver. Indirect TPMSs
do not have tire pressure sensors. Current indirect TPMSs rely on the
wheel speed sensors in an anti-lock braking system (ABS) to detect and
compare differences in the rotational speed of a vehicle's wheels.
Those differences correlate to differences in tire pressure because
decreases in tire pressure cause decreases in tire diameter that, in
turn, cause increases in wheel speed.
To meet the four-tire, 20 percent alternative, vehicle
manufacturers likely would have had to use direct TPMSs because even
improved indirect systems would not likely be able to detect loss of
pressure until pressure has fallen 25 percent and could not detect all
combinations of significantly under-inflated tires. To meet the three-
tire, 25 percent alternative, vehicle manufacturers would have been
able to install either direct TPMSs or improved indirect TPMSs, but not
current indirect TPMSs.
B. Highlights of the Preliminary Determination About the Final Rule
NHTSA preliminarily determined to issue a final rule that would
have specified a four-year phase-in schedule\1\ and allowed compliance
with either of two options during the phase-in, i.e., between November
1, 2003 and October 31, 2006. Under the first option, a vehicle's TPMS
would have had to warn the driver when the pressure in one or more of
the vehicle's tires, up to a total of four tires, was 25 percent or
more below the placard pressure, or a minimum level of pressure
specified in the standard, whichever pressure was higher. (This option
is referred to below as the four-tire, 25 percent option.) Under the
second option, a vehicle's TPMS would have had to warn the driver when
the pressure in any one of the vehicle's tires was 30 percent or more
below the placard pressure, or a minimum level of pressure specified in
the standard, whichever pressure was higher. (This option is referred
to below as the one-tire, 30 percent option.) The minimum levels of
pressure specified in the standard were the same for both compliance
options.
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\1\ The phase-in schedule was as follows: 10 percent of a
manufacturer's affected vehicles would have had to comply with
either compliance option in the first year; 35 percent in the second
year; and 65 percent in the third year. In the fourth year, 100
percent of a manufacturer's affected vehicles would have had to
comply with the long-term requirements, i.e., the four-tire, 25
percent compliance option.
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After the phase-in, i.e., after October 31, 2006, the second option
would have been terminated, and the provisions of the first option
would have become mandatory for all new vehicles. Thus, all vehicles
would have been required to meet a four-tire, 25 percent requirement.
C. OMB Return Letter
After reviewing the draft final rule, OMB returned it to NHTSA for
reconsideration, with a letter explaining its reasons for doing so, on
February 12, 2002. In the letter, OMB stated its belief that the draft
final rule and accompanying regulatory impact analysis did not
adequately demonstrate that the agency had selected the best available
method of improving overall vehicle safety.
D. Highlights of the Final Rule
In response to the OMB return letter, the agency has decided to
divide the final rule into two parts. The first part is contained in
this document, which establishes requirements for vehicles manufactured
during the first three years, i.e., between November 1, 2003, and
October 31, 2006, and phases them in by increasing percentages of
production. The second part will establish requirements for vehicles
manufactured on or after November 1, 2006.
The agency has divided the final rule into two parts because it has
decided to
[[Page 38706]]
defer its decision as to which long-term performance requirements for
TPMS would best satisfy the mandate of the TREAD Act. This deferral
will allow the agency's consideration of additional data on the effect
and performance of TPMSs. From the beginning, the agency has sought to
comply with the mandate and safety goals of the TREAD Act in a way that
encourages innovation and allows a range of technologies to the extent
consistent with providing drivers with sufficient warning of low tire
pressure under a broad variety of the reasonably foreseeable
circumstances in which tires become under-inflated.
1. Part One--Phase-in (November 2003 through October 2006)
NHTSA has decided to require vehicle manufacturers to equip their
light vehicles (i.e., those with a gross vehicle weight rating (GVWR)
of 10,000 lbs. or less) with TPMSs and to give them the option for
complying with either of two sets of performance requirements during
the period covered by the first part of the final rule, i.e., from
November 1, 2003 to October 31, 2006. The options are the same as those
in the preliminary determination about the final rule.
Under the first set or compliance option, the vehicle's TPMS will
be required to warn the driver when the pressure in any single tire or
in each tire in any combination of tires, up to a total of four tires,
is 25 percent or more below the vehicle manufacturer's recommended cold
inflation pressure for the tires, or a minimum level of pressure
specified in the standard, whichever pressure is higher. Under the
second compliance option, the vehicle's TPMS will be required to warn
the driver when the pressure in any single tire is 30 percent or more
below the vehicle manufacturer's recommended cold inflation pressure
for the tires, or a minimum level of pressure specified in the
standard, whichever pressure is higher.\2\
The two compliance options are outgrowths of the alternative sets
of requirements proposed in the NPRM. In response to comments
confirming that current indirect TPMSs cannot meet the proposed three-
tire, 25 percent under-inflation requirements, and in order to allow
those systems to be used during the phase-in, the agency is adopting
requirements for detection of one-tire, 30 percent under-inflation as
the first option. For the second option, the agency is adopting
requirements for detection of 4-tire, 25 percent under-inflation.
Adopting those requirements, instead of the proposed requirements for
four-tire, 20 percent under-inflation, will permit manufacturers to use
either direct TPMSs or hybrid TPMSs, i.e., TPMSs that combine direct
and indirect TPMS technologies. One TPMS supplier indicated the
potential for developing and producing hybrid systems, although it also
indicated that it did not currently have plans for doing so. The agency
believes that the difference in benefits between TPMSs meeting four-
tire, 20 percent requirements and TPMSs meeting four-tire, 25 percent
requirements should not be substantial.
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\2\ The minimum levels of pressure are the same for both
compliance options.
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To facilitate compliance with the options, the rule phases them in
by increasing percentages of production. Ten percent of a vehicle
manufacturer's light vehicles will be required to comply with either
compliance option during the first year (November 1, 2003 to October
31, 2004), 35 percent during the second year (November 1, 2004 to
October 31, 2005), and 65 percent during the third year (November 1,
2005 to October 31, 2006). These percentages are the same as those in
the preliminary determination about the final rule. The agency is
allowing carry-forward credits for vehicles that are manufactured
during the phase-in and are equipped with TPMSs that comply with the
four-tire, 25 percent option. It is not allowing credits for TPMSs
complying with the other option for the same reason that the agency is
requiring manufacturers to provide consumers with information about the
performance limitations of those systems.
The combination of the two compliance options and the phase-in will
allow manufacturers to continue to use current indirect TPMSs during
that period and ease the implementation of the TPMS standard. The
agency notes that, for vehicles already equipped with ABS, the
installation of a current indirect TPMS is the least expensive way of
complying with a TPMS standard. The compliance options and phase-in
will also give manufacturers the flexibility needed to innovate and
improve the performance of their TPMSs. This flexibility will improve
the chances that ways can be found to improve the detection of under-
inflation as well as reduce the costs of doing so.
The owner's manual for vehicles certified to either compliance
option will be required to include written information explaining the
purpose of the low tire pressure warning telltale, the potential
consequences of driving on significantly under-inflated tires, the
meaning of the telltale when it is illuminated, and the actions that
drivers should take when the telltale is illuminated. In addition, the
owner's manual in vehicles certified to the one-tire, 30 percent option
will be required to include information on the inherent performance
limitations of current indirect TPMSs because the agency anticipates
that most indirect TPMSs installed to comply with that option will
exhibit those limitations and because a vehicle owner survey indicates
that a significant majority of drivers would be less concerned, to
either a great extent or a very great extent, with routinely
maintaining the pressure of their tires if their vehicle were equipped
with a TPMS. Under both compliance options, the TPMS will be required
to have a low tire pressure-warning telltale (yellow).
2. Part Two--November 2006 and Thereafter
Beginning November 1, 2006, all passenger cars and light trucks,
multipurpose passenger vehicles, and buses under 10,000 pounds GVWR
will be required to comply with the requirements in the second part of
this final rule. The agency will publish the second part of this final
rule by March 1, 2005, in order to give manufacturers sufficient lead
time before vehicles must meet the requirements.
In anticipation of making the decision in part two of this final
rule about the long-term requirements, the agency will leave the
rulemaking docket open for the submission of new data and analyses. The
agency also will conduct a study comparing the tire pressures of
vehicles without any TPMS to the pressures of vehicles with TPMSs that
do not comply with the four-tire, 25 percent compliance option. When
completed, it will be placed in the docket for public examination.
After consideration of the record compiled to this date, as
supplemented by the results of the tire pressure study and any other
new information submitted to the agency, NHTSA will issue the second
part of this rule by March 1, 2005.
Based on the record now before the agency, NHTSA tentatively
believes that the four-tire, 25 percent option would best meet the
mandate in the TREAD Act. However, it is possible that the agency may
obtain or receive new information that is sufficient to justify a
continuation of the compliance options established by the first part of
this final rule, or the adoption of some other alternative.
[[Page 38707]]
E. Summary Comparison of the Preliminary Determination and the Final
Rule
The primary difference between the preliminary determination and
the final rule is one of timing, instead of substance. The options and
percentages of production for the phase-in years are unchanged.\3\ The
final rule does differ from the preliminary determination in the timing
of the agency's decision about the performance requirements for the
years following the phase-in period.
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\3\ The final rule does require that additional information be
placed in the vehicle's owner manual.
Summary Comparison of the Preliminary Determination and the Final Rule
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Preliminary
determination Final rule
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Application................... Passenger cars, Same.
trucks, multipurpose
passenger vehicles,
and buses with a GVWR
of 10,000 pounds or
less, except those
vehicles with dual
wheels on an axle.
Short-term (11/1/03--10/31/
06):
Compliance Options............ Option 1: TPMS must Same.
warn the driver when
the pressure in any
single tire or in
each tire in any
combination of tires,
up to a total of four
tires, has fallen to
25 percent or more
below the vehicle
manufacturer's
recommended cold
inflation pressure
for the tires, or a
minimum level of
pressure specified in
the standard,
whichever pressure is
higher.
Option 2: TPMS must Same.
warn the driver when
the pressure in any
single tire has
fallen to 30 percent
or more below the
vehicle
manufacturer's
recommended cold
inflation pressure
for the tires, or a
minimum level of
pressure specified in
the standard,
whichever pressure is
higher.
Phase-in Schedule............. 10% of a vehicle Same.
manufacturer's light
vehicles will be
required to comply
with either
compliance option
during the first year
(November 1, 2003 to
October 31, 2004), 35
percent during the
second year (November
1, 2004 to October
31, 2005), and 65
percent during the
third year (November
1, 2005 to October
31, 2006).
Long-term (11/1/06 &
thereafter):
Performance Requirements...... TPMS must warn the Decision to be
driver when the made by March
pressure in any 1, 2005.
single tire or in
each tire in any
combination of tires,
up to a total of four
tires, has fallen to
25 percent or more
below the vehicle
manufacturer's
recommended cold
inflation pressure
for the tires, or a
minimum level of
pressure specified in
the standard,
whichever pressure is
higher.
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II. Background
A. The Transportation Recall Enhancement, Accountability, and
Documentation Act
Congress enacted the TREAD Act on November 1, 2000.\4\ Section 13
of the TREAD Act mandated the completion of ``a rulemaking for a
regulation to require a warning system in new motor vehicles to
indicate to the operator when a tire is significantly under inflated''
within one year of the TREAD Act's enactment. Section 13 also requires
the regulation to take effect within two years of the completion of the
rulemaking.
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\4\ Public Law 106-414.
\5\ Tri-Level Study of the Causes of Traffic Accidents, Treat,
J.R., et al. (1979) (Contract No. DOT HS 034-3-535), DOT HS 805 099,
Washington, DC: U.S. Department of Transportation, National Highway
Traffic Safety Administration.
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B. Previous Rulemaking on Tire Pressure Monitoring Systems
NHTSA first considered requiring a ``low tire pressure warning''
device in 1970. However, the agency determined that the only warning
device available at that time was an in-vehicle indicator whose cost
was too high.
During the 1970s, several manufacturers developed inexpensive, on-
tire warning devices. In addition, the price of in-vehicle warning
devices dropped significantly.
As a result, on January 26, 1981, NHTSA published an Advanced
Notice of Proposed Rulemaking (ANPRM) soliciting public comment on
whether the agency should propose a new Federal motor vehicle safety
standard requiring each new motor vehicle to have a low tire pressure
warning device which would ``warn the driver when the tire pressure in
any of the vehicle's tires was significantly below the recommended
operating levels.'' (46 FR 8062.)
NHTSA noted in the ANPRM that under-inflation increases the rolling
resistance of tires and, correspondingly, decreases the fuel economy of
vehicles. Research data at the time indicated that the under-inflation
of a vehicle's radial tires by 10 pounds per square inch (psi) reduced
the fuel economy of the vehicle by 3 percent. Because of the worldwide
oil shortages in the late 1970s and early 1980s, NHTSA was interested
in finding ways to increase the fuel economy of passenger vehicles
(i.e., passenger cars and multipurpose passenger vehicles). Since
surveys by the agency showed that about 50 percent of passenger car
tires and 13 percent of truck tires were operated at pressures below
the vehicle manufacturer's recommended (placard) pressure, the agency
believed that low tire pressure warning devices would encourage drivers
to maintain their tires at the proper inflation level, thus maximizing
their vehicles' fuel economy.
Moreover, a 1977 study by Indiana University concluded that under-
inflated tires were a probable cause of 1.4 percent of all motor
vehicle crashes.\5\ Based on that figure, and the approximately 18.3
million motor vehicle crashes then occurring annually in the United
States, the agency suggested that under-inflated tires were probably
responsible for 260,000 crashes each year (1.4 percent x 18.3 million
crashes).
In the ANPRM, NHTSA sought answers from the public to several
questions, including:
(1) What tire pressure level should trigger the warning device?
[[Page 38708]]
(2) Should the agency specify the type of warning device (i.e., on-
tire or in-vehicle) to be used?
(3) What would it cost to produce and install an on-tire or in-
vehicle warning device?
(4) What is the fuel saving potential of low tire pressure warning
devices?
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\5\ Tri-Level Study of the Causes of Traffic Accidents, Treat,
J.R., et al. (1979) (Contract No. DOT HS 034-3-535), DOT HS 805 099,
Washington, DC: U.S. Department of Transportation, National Highway
Traffic Safety Administration.
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(5) What studies have been performed which would show cause and
effect relationships between low tire pressure and auto crashes?
(6) What would be the costs and benefits of a program to educate
the public on the benefits of maintaining proper tire pressure?
NHTSA terminated the rulemaking on August 31, 1981, because public
comments indicated that the low tire pressure warning devices available
at the time either had not been proven to be accurate and reliable (on-
tire devices) or were too expensive (in-vehicle devices). (46 FR
43721.) The comments indicated that in-vehicle warning devices had been
proven to be accurate and reliable, but would have had a retail cost of
$200 (in 1981 dollars) per vehicle. NHTSA stated, ``Such a cost
increase cannot be justified by the potential benefits, although those
benefits might be significant.'' (46 FR 43721.) The comments also
indicated that on-tire warning devices cost only about $5 (in 1981
dollars), but they had not been developed to the point where they were
accurate and reliable enough to be required. The comments also
suggested that on-tire warning devices were subject to damage by road
hazards, such as ice and mud, as well as scuffing at curbs. Despite
terminating the rulemaking, the agency stated that it still believed
that ``[m]aintaining proper tire inflation pressure results in direct
savings to drivers in terms of better gas mileage and longer tire life,
as well as offering increased safety.'' (46 FR 43721.)
C. Summary of the Notice of Proposed Rulemaking
On July 26, 2001, the agency published the NPRM proposing to
establish a standard for TPMSs pursuant to section 13 of the TREAD Act.
(66 FR 38982.) The agency proposed two alternative versions of the
standard.
The two alternatives differed in two important respects: in how
they defined ``significantly under-inflated,'' and in the number of
significantly under-inflated tires that they would be required to be
able to detect at any one time. The first alternative (four tires, 20
percent) would have defined ``significantly under-inflated'' as the
tire pressure 20 percent or more below the placard pressure, or a
minimum level of pressure specified in the standard, whichever was
higher. It would have required the low tire pressure warning telltale
to illuminate when any tire, or when each tire in any combination of
tires, on the vehicle became significantly under-inflated.
The second alternative (three tires, 25 percent) would have defined
``significantly under-inflated'' as the tire pressure 25 percent or
more below the placard pressure, or a minimum level of pressure
specified in the standard, whichever was higher. The minimum levels of
pressure were the same in both proposed alternatives. The alternative
would have required the low tire pressure warning telltale to
illuminate when any tire, or when each tire in any combination of
tires, up to a total of three tires, became significantly under-
inflated.
In most other respects, the two alternatives were identical. Both
would have required passenger cars, multipurpose passenger vehicles,
trucks, and buses with a GVWR of 4,536 kilograms (10,000 pounds) or
less, manufactured on or after November 1, 2003, to be equipped with a
TPMS and a low tire pressure warning telltale (yellow) to alert the
driver. They would have required the telltale to illuminate within 10
minutes of driving after any tire on the vehicle became significantly
under-inflated. They would have required the telltale to remain
illuminated as long as any of the vehicle's tires remained
significantly under-inflated, and the key locking system was in the
``On'' (``Run'') position. They would have required that the telltale
be deactivatable, manually or automatically, only when the vehicle no
longer had a tire that was significantly under-inflated. They would
have required the TPMS in each vehicle to be compatible with all
replacement or optional tires/rims of the size recommended for that
vehicle by the vehicle manufacturer, i.e., each TPMS would have been
required to continue to meet the requirements of the standard when the
vehicle's original tires were replaced with tires of any optional or
replacement size(s) recommended for the vehicle by the vehicle
manufacturer. Finally, they would have required vehicle manufacturers
to provide written instructions, in the owner's manual if one is
provided, explaining the purpose of the low tire pressure warning
telltale, the potential consequences of significantly under-inflated
tires, and what actions drivers should take when the low tire pressure
warning telltale is illuminated.
NHTSA believed that the only currently available TPMSs that would
have been able to meet the requirements of the four-tire, 20 percent
alternative were direct TPMSs. There were two reasons for this belief.
First, currently available indirect TPMSs typically cannot detect
significant under-inflation until the pressure in one of the vehicle's
tires is about 30 percent below the pressure in at least some of the
other tires. Second, they cannot detect when all four tires lose
inflation pressure equally.
The agency believed that both currently available direct TPMSs and
improved indirect TPMSs, but not current indirect TPMSs, would have
been able to meet the requirements of the three-tire, 25 percent
alternative.
In the NPRM, NHTSA anticipated that vehicle manufacturers would
minimize their costs of complying with the three-tire, 25 percent
alternative by installing improved indirect TPMSs in vehicles already
equipped with ABSs and direct TPMSs in vehicles without ABSs. For
vehicles already equipped with an ABS, the cost of modifying that
system to serve the additional purpose of indirectly monitoring tire
pressure would be significantly less than the cost of adding a direct
TPMS. For vehicles not so equipped, adding a direct TPMS would be
significantly less expensive than adding ABS to monitor tire pressure.
For the NPRM, NHTSA had two sets of data, one from Goodyear and
another from NHTSA's Vehicle Research and Test Center (VRTC), on the
effect of under-inflated tires on a vehicle's stopping distance. The
Goodyear data indicated that a vehicle's stopping distance on wet
surfaces is significantly reduced when its tires are properly inflated,
as compared to when its tires are significantly under-inflated. The
VRTC data indicated little or no effect on a vehicle's stopping
distance. For purposes of the NPRM, NHTSA used the Goodyear data to
establish an upper bound of benefits and the VRTC data to establish a
lower bound. The benefit estimates below are the mid-points between
those upper and lower bounds.
NHTSA estimated that the four-tire, 20 percent alternative would
have prevented 10,635 injuries and 79 deaths at an average net cost of
$23.08 per vehicle.\6\ NHTSA estimated that the
[[Page 38709]]
three-tire, 25 percent alternative would have prevented 6,585 injuries
and 49 deaths at an average net cost of $8.63 per vehicle.\7\ NHTSA
estimated that the net cost per equivalent life saved would have been
$1.9 million for the four-tire, 20 percent alternative and $1.1 million
for the three-tire, 25 percent alternative.
---------------------------------------------------------------------------
\6\ 6 The range of injuries prevented was 0 to 21,270, and the
range of deaths prevented was 0 to 158. These benefit estimates did
not include deaths and injuries prevented due to reductions in
crashes caused by blowouts and skidding/loss of control because the
agency was unable to quantify those benefits at the time the NPRM
was published. For this final rule, the agency was able to quantify
those benefits. They are discussed in the Benefits section below.
Net costs included $66.33 in vehicle costs minus $32.22 in fuel
savings and $11.03 in tread wear savings. These cost estimates did
not include maintenance costs. For this final rule, the agency has
estimated maintenance costs. They are discussed in the Costs section
below.
\7\ The range of injuries prevented was 0 to 13,170, and the
range of deaths prevented was 0 to 97. Net costs included $30.54 in
vehicle costs minus $16.40 in fuel savings and $5.51 in tread wear
savings. These estimates did not include maintenance costs. The
agency has estimated maintenance costs for this final rule.
---------------------------------------------------------------------------
Finally, the agency requested comments on whether a compliance
phase-in with carry-forward credits would be appropriate. The agency
suggested a phase-in period of 35 percent of production in the first
year (2003), 65 percent in the second year, and 100 percent in the
third year.
D. Summary of Public Comments on Notice
The agency received comments from tire, vehicle, and TPMS
manufacturers, consumer advocacy groups, and the general public. In
general, the tire manufacturers' comments, including the comments of
the international tire industry associations European Tyre and Rim
Technical Organisation (ETRTO), Japan Automobile Tyre Manufacturers
Association (JATMA), and International Tire & Rubber Association
(ITRA), echoed the comments of the Rubber Manufacturers Association
(RMA). In general, the vehicle manufacturers' comments, including the
comments of the Association of International Automobile Manufacturers
(AIAM), were similar to the comments of the Alliance of Automobile
Manufacturers (Alliance).
The tire manufacturers generally supported the four-tire, 20
percent alternative. The vehicle manufacturers generally supported
requirements that would permit both direct and current indirect TPMSs
to comply. TPMS manufacturers generally supported the alternative that
would allow the type of system they manufacture. The consumer advocacy
groups--Consumers Union and Advocates for Highway and Auto Safety
(Advocates) supported by Public Citizen, Consumer Federation of
America, and Trauma Foundation--generally supported the four-tire, 20
percent alternative. The general public was about evenly divided
between those who supported and those who opposed a Federal standard
requiring TPMSs.
The major issues discussed by the commenters are summarized below.
The comments are addressed in the discussion of the final rule below
1. Vehicles Covered
The agency proposed to require TPMSs on passenger cars,
multipurpose passenger vehicles, trucks, and buses with a GVWR of 4,536
kilograms (10,000 pounds) or less. The agency did not propose to
require TPMSs on motorcycles, trailers, or low speed vehicles, or on
medium (10,001-26,000 pounds GVWR) vehicles, or heavy (greater than
26,000 pounds GVWR) vehicles for reasons explained in the NPRM.
The Alliance recommended that the agency limit the applicability of
the standard to these types of vehicles to those having a GVWR of 3,856
kilograms (8,500 pounds or less). The Alliance stated that the majority
of vehicles above 8,500 pounds GVWR are used commercially. The Alliance
argued that those vehicles are maintained on a regular basis and do not
need a TPMS to assist in maintaining proper inflation pressure in the
vehicles' tires.
The Alliance also recommended that the agency explicitly exclude
incomplete vehicles, i.e., vehicles that are built in more than one
stage, from the standard. Normally, the first-stage vehicle
manufacturer is responsible for certifying that all vehicle systems
that are not directly modified by subsequent-stage manufacturers meet
all Federal motor vehicle safety standards. The Alliance stated that in
the case of direct TPMSs, the first-stage manufacturer will be unable
to guarantee that, even if physically undisturbed, a non-defective TPMS
will function as designed after vehicle modifications (such as adding
metal hardware to the vehicle or lengthening its wheelbase) are made by
subsequent-stage manufacturers.
Advocates recommended that the agency expand the application of the
standard to include medium (10,001-26,000 pounds GVWR) and heavy (over
26,000 pounds) trucks and buses. Advocates stated that tire under-
inflation is a pervasive problem with these vehicles, especially given
the high percentage of these vehicles that are equipped with re-treaded
tires.
2. Phase-In Options and Long-Term Requirements
a. Definition of ``Significantly Under-Inflated''
RMA recommended that the agency define ``significantly under-
inflated'' as any inflation pressure that is less than the pressure
required to carry the actual vehicle load on the tire per tire industry
standards (or any pressure required to carry the maximum vehicle load
on the tire if the actual load is unknown), or the minimum activation
pressure specified in the standard, whichever is higher. RMA argued
that some vehicles have a placard pressure that is barely adequate to
carry the vehicle's maximum load. If the tire pressure falls 20 or 25
percent below the placard pressure, the tire pressure will be
insufficient to carry the load. RMA stated that the definition of
``significantly under-inflated'' should not be tied to placard pressure
unless the standard includes a requirement for all vehicles to have a
reserve in the placard pressure above a specified minimum (e.g., 20 or
25 percent).
RMA also recommended that the agency change the minimum activation
pressures for P-metric standard load tires from 20 to 22 psi and for P-
metric extra load tires from 23 to 22 psi. Finally, RMA recommended
that the agency change the ``Maximum Pressure'' heading in Table 1 to
``Maximum or Rated Pressure'' because light truck tires are not subject
to maximum permissible inflation pressure labeling requirements. RMA
recommended that the agency change the rated pressure for Load Range E
tires from 87 to 80 psi. Finally, RMA, supported by the Retread/Repair
Industry Government Advisory Council (RIGAC),\8\ recommended that the
agency adopt, in this rulemaking proceeding, an amendment to upgrade
Standard No. 109, ``New Pneumatic Tires,'' by requiring that ``a tire
for a particular vehicle must have sufficient inflation and load
reserve, such that an inflation pressure 20 or 25 percent less than the
vehicle manufacturer's recommended inflation pressure is sufficient for
the vehicle maximum load on the tire, as defined by FMVSS-110.'' \9\
---------------------------------------------------------------------------
\8\ RIGAC consists of representatives from the Tire Association
of North America (TANA), Tread Rubber Manufacturers Group (TRMG),
ITRA, and RMA.
\9\ Standard No. 110 specifies requirements for tire selection
to prevent tire overloading.
---------------------------------------------------------------------------
The ITRA recommended that the agency consider only direct TPMSs.
The ITRA stated that indirect TPMSs have too many limitations,
including the inability to detect when all four of a vehicle's tires
are significantly under-inflated. The ITRA claimed that, although
direct TPMSs are more expensive than indirect TPMSs, their cost is
minor when compared to their safety, handling, tread wear, and fuel
economy benefits.
The Alliance recommended that the agency define ``significantly
under-inflated'' as any inflation pressure 20 percent below a tire's
load carrying
[[Page 38710]]
limit, as determined by a tire industry standardizing body (such as the
Tire and Rim Association) or the minimum activation pressure specified
in the standard, whichever is higher. The Alliance agreed with the
agency's minimum activation pressure of 20 psi for P-metric standard
load tires. The Alliance cited data from tests performed by RMA
indicating that the average tire was able to operate at high speeds
(120 and 140 km/h) at load-inflation conditions more extreme than the
worst case that the Alliance proposal would allow.
The Alliance also stated that a 25 percent differential from
placard pressure would be inadequate to allow the use of indirect
TPMSs. The Alliance claimed that a minimum of 30 percent differential
is necessary to ensure accuracy with an indirect TPMS and avoid
excessive nuisance warnings.
The AIAM recommended that the agency define ``significantly under-
inflated'' as any pressure more than 30 percent below the placard
pressure. Alternatively, the AIAM suggested that the agency use the
load-carrying limit of the tire as defined by a tire industry
standardizing body as the baseline for determining the warning
threshold.
Several manufacturers indicated that they are either developing or
could develop indirect or hybrid TPMSs that perform better than current
indirect TPMSs. In its comments on the NPRM, TRW Automotive Electronics
(TRW), which manufactures both direct and indirect TPMSs, stated that
it could, in concept, combine direct and indirect TPMS technologies to
produce a hybrid TPMS that performs better than TRW's current indirect
TPMS. TRW stated this could be accomplished by adding the equivalent of
two direct pressure-monitoring sensors and a radio frequency receiver
to an indirect TPMS. TRW suggested that this hybrid TPMS could comply
detect 25 under-inflation for about 60 percent of the cost of a full
direct TPMS. However, it did not indicate whether it had any plans to
develop a hybrid system.
Sumitomo Rubber Industries, which manufactures indirect TPMSs,
indicated that indirect TPMSs will be able to detect a 25 percent
differential in inflation pressure.
Toyota, which uses an indirect TPMS on its Sienna van, stated that
its next generation of indirect TPMSs (i.e., TPMSs not available for
current production) would be able to detect a 20 percent differential
in tire pressure by monitoring the resonance frequency as well as the
dynamic radius changes of the tires. However, Toyota stated that this
performance will be achieved only under ideal conditions, i.e., the
vehicle is traveling in a relatively straight line at 30 to 60 km/h for
at least 20 minutes. Thus, Toyota recommended that the agency adopt the
Alliance proposal of 30 percent under-inflation. Toyota also stated
that its next generation of indirect TPMSs would be able to detect
significant under-inflation in all four tires. Toyota was not certain
when its next generation of indirect TPMSs will be ready for
implementation.
Advocates supported the definition of ``significantly under-
inflated'' contained in the four-tire, 20 percent alternative, i.e.,
any pressure 20 percent or more below the placard pressure, or the
minimum activation pressure specified in the standard. Advocates also
supported the agency's minimum activation pressures.
b. Number of Tires Monitored
Advocates, the ITRA, and RMA recommended that the agency require
TPMSs to be able to detect when all four of a vehicle's tires become
significantly under-inflated. RMA argued that it is very likely that
all four tires will lose air pressure at a similar rate and become
significantly under-inflated within a six-month period.\10\ RMA stated
that drivers would rely heavily on TPMSs for tire pressure maintenance,
which will make this scenario even more likely.
---------------------------------------------------------------------------
\10\ RMA stated that normal air pressure loss is approximately 1
to 2 psi per month.
---------------------------------------------------------------------------
The Alliance and AIAM recommended that the agency require only that
TPMSs be able to detect significant under-inflation in a single tire.
The Alliance argued that TPMSs are not meant to replace the normal tire
maintenance that would detect pressure losses due to natural leakage
and permeation. Instead, TPMSs are intended to detect a relatively slow
leak due to a serviceable condition, such as a nail through the tread
or a leaky valve stem. Since such leaks rarely affect more than one
tire simultaneously, the Alliance argued, it is sufficient to require
only that TPMSs be able to detect a single significantly under-inflated
tire. In further support of this position, the Alliance argued that
tires do not lose pressure at the same rate.
As noted above, TRW commented that a hybrid TPMS could be developed
that would be capable of monitoring all four of a vehicle's tires.
According to TRW, a hybrid system would involve installing two direct
pressure sensors, one in a front wheel and one in a back wheel located
diagonally from each other (e.g., the front left and back right
wheels), on a vehicle already equipped with an indirect TPMS. The
pressure sensors would directly monitor the pressure in those two
tires, while the indirect TPMS would use the wheel speed sensors to
indirectly monitor the pressure in the other two tires. This would
solve the problem indirect TPMSs have in detecting when two tires on
the same axle or the same side of the vehicle become significantly
under-inflated because a direct pressure sensor will be in a wheel on
each axle and on each side of the vehicle. It would also solve the
problem indirect TPMSs have in detecting when all four tires become
significantly under-inflated.
Advocates and RMA also recommended that the agency require TPMSs to
monitor a vehicle's spare tire. RMA argued that the spare tire should
be monitored to ensure its functionality, if and when it is needed.
Advocates stated, ``Vehicle owners chronically neglect to maintain
minimal air pressure in spare tires.''
The Alliance recommended that the agency require only that TPMSs
monitor full-size, matching spare tires, and only when they are
installed on the vehicle (i.e., not when they are stowed). The Alliance
stated that temporary-use spare tires, including full-size, non-
matching and compact spare tires, are not intended to be part of the
normal tire rotation cycle for the vehicle. Because these temporary-use
spare tires degrade the aesthetic appearance of a vehicle or have speed
and distance limitations, vehicle owners normally replace them quickly.
Thus, the Alliance recommended that the agency not require TPMSs to
monitor temporary-use tires, whether stowed or installed on the
vehicle.
RMA supported the agency's proposed requirement that TPMSs function
properly with all replacement tires and rims of the size(s) recommended
by the vehicle manufacturer. Advocates recommended that the agency
require TPMSs to function properly with all replacement tires and rims,
regardless of size.
The Alliance recommended that the agency require only that TPMSs
function properly with those tires and rims offered as original or
optional equipment by the vehicle manufacturer. The Alliance stated
that there are a large number of replacement brands and types of tires
and rims with different dynamic rolling radii, size variations, load
variations, and temperature characteristics. The Alliance argued that
since vehicle manufacturers do not control tire compliance for
aftermarket tires and rims, they could not guarantee that the TPMS will
work, or will work with the same level of precision, in all cases.
[[Page 38711]]
3. Lead Time
The Alliance and most vehicle manufacturers recommended the
following four-year phase-in schedule: 15 percent of a manufacturer's
affected products equipped with a semi- or fully-compliant TPMS in the
first year; 35 percent in the second year; 70 percent in the third
year; and 100 percent of a manufacturer's affected products equipped
with a fully compliant TPMS in the final year. According to the
Alliance, a semi-compliant TPMS is one that meets all but specified
interface requirements, i.e., those concerning the display of
information about under-inflation, and would be allowed only during the
phase-in period. The Alliance and AIAM also recommended that the agency
provide credits for early introduction of TPMSs to encourage early
implementation of the standard.
TRW supported the agency's four-year phase-in period. TRW stated
that direct TPMSs are ready so that manufacturers could start
production to meet such a phase-in. However, TRW stated that the
improvements in indirect TPMSs that will be necessary to meet the
requirements of this final rule would make it difficult to meet the
compliance date of November 1, 2003.
Ford Motor Company (Ford) commented that its recent experience with
direct TPMSs demonstrates that this technology still needs a thorough
prove-out. Ford stated that when it tested 138 direct pressure sensors
on 30 vehicles, nine sensors experienced a malfunction. This translates
to a sensor failure rate of 6.5 percent. However, Ford stated that if
the final rule required five sensors per vehicle (all four tires plus
the spare tire), nearly 33 percent of vehicles could experience the
failure of at least one sensor. Ford recommended that the agency adopt
the phase-in schedule set forth by the Alliance.
Vehicle Services Consulting, Inc. (VSC), which submitted comments
on behalf of small volume vehicle manufacturers (i.e., those
manufacturers who produce fewer than 5,000 vehicles worldwide each
year), recommended that the agency provide phase-in discretion so that
small volume manufacturers have until the end of the phase-in period
before having to comply with the TPMS requirements. VSC claimed that
small volume manufacturers could not obtain the TPMS technology at the
same time as large volume manufacturers.
4. Reliability
In the NPRM, the agency noted that the components of direct TPMSs,
especially when tires are taken off the rim, might be susceptible to
damage. The agency requested comments on the likelihood of such damage.
TRW stated:
Direct TPMSs are relatively new systems and, therefore, the
likelihood of damage during driving or maintenance is unknown.
However, direct TPMS sensors are designed to minimize the likelihood
of damage during driving or maintenance operations. Most sensors are
valve-mounted and rest in the drop center well of the rim, and are
contoured to minimize the likelihood of damage during tire
servicing. They can be packaged in a high impact plastic material,
which can withstand high G forces and mechanical vibration/shock
levels associated with the tire/wheel system. The likelihood of
damage during operation is also minimized by the selected mounting
location and the protection offered by the rim during flat
conditions. These factors, combined with training for service center
technicians, should reduce the overall likelihood of damage.
Beru Corporation, which manufacturers direct TPMSs, stated that it
had sold over 800,000 direct TPMS wheel electronics and had received no
reports of damage during operation or failures due to mounting error.
The European Community (EC) supported a rulemaking requiring TPMSs.
The EC Stated, ``The European Community is convinced (as is the NHTSA)
of the appropriateness of a regulation in this field, and of its
justification for the safety of road users.'' The EC stressed ``the
paramount importance of reliability and accuracy of the technology.''
The EC stated that ``a temperature correction device might be a
necessary feature in order to guarantee the reliability and accuracy of
the device.''
5. Costs and Benefits Estimates
The Alliance stated that the benefits NHTSA estimated resulting
from a reduction in stopping distance were based on three principal
conclusions: (1) Properly inflated tires result in shorter stopping
distances than under-inflated tires; (2) these shorter stopping
distances have equal safety benefits in all types of crashes and under
all environmental conditions; and (3) the benefits of shorter stopping
distances associated with properly-inflated tires will be greater for
direct TPMSs than for indirect TPMSs. The Alliance argued that each of
these conclusions is highly questionable and not supported by the
information in the rulemaking record.
The Alliance noted that in estimating the safety benefits resulting
from stopping distance reductions, the agency relied on Goodyear data.
The Alliance argued that these data ``are neither conclusive with
respect to the effect of under-inflation on stopping distance, nor
reproducible according to the agency's own study demonstrating that
there is no significant effect of tire under-inflation on stopping
distance.'' The Alliance also argued that even if the Goodyear data
were valid, NHTSA's benefits estimates must be adjusted to claim
benefits only for vehicles experiencing the same conditions as those in
the Goodyear tests, i.e., all four of the vehicle's tires are at 17 psi
or below and on wet pavement.\11\ The Alliance questioned NHTSA's
assumption that 80 percent of drivers would respond appropriately to a
direct TPMS, but that only 60 percent of drivers would respond
appropriately to an indirect TPMS. The Alliance argued that there was
no evidence in the record supporting this assumption.
---------------------------------------------------------------------------
\11\ Goodyear conducted its tests on pavement with 0.05 inch
water on the surface and found significant effects on stopping
distance only when the pressure in the vehicle's tires was lowered
to 17 psi.
---------------------------------------------------------------------------
Finally, the Alliance agreed that TPMSs should produce some of the
unquantified benefits listed in the NPRM. However, the Alliance stated
that there was no evidence that these benefits would be greater for
direct TPMSs than for indirect TPMSs.
The ITRA stated that when developing training programs, it looks
closely at tire performance and has the opportunity to analyze a
significant number of tires that failed in service. They find that the
single most common cause of tire failure is under-inflation. Thus, the
ITRA claimed that the agency's benefits estimates may be under-stated.
TRW stated that current indirect TPMSs would have to be upgraded to
meet the requirements of the three-tire, 25 percent alternative. TRW
estimated that these upgrades would increase the cost of indirect TPMSs
to 60 percent of the cost of a direct TPMS.\12\
---------------------------------------------------------------------------
\12\ This estimate would apply only to vehicles that were
already equipped with ABS.
---------------------------------------------------------------------------
IQ-mobil Electronics, a TPMS manufacturer in Germany, commented
that it has developed ``a batteryless transponder chip'' that ``costs
half as much as the battery transmitter it replaces,'' thus reducing
``high replacement costs for the tire transmitter, and an annual
environmental burden of millions of batteries.''
E. Submission of Draft Final Rule to OMB
Since this final rule is considered ``significant'' under Executive
Order 12866, Regulatory Planning and Review, it was subject to review
by the Office of Management and Budget (OMB) under that Order. The
agency submitted a draft
[[Page 38712]]
final rule to OMB on December 18, 2001.
The draft final rule specified short and long-term performance
requirements.\13\ For the short term, it specified a phase-in of the
TPMS requirements beginning November 1, 2003. During the phase-in, the
draft final rule permitted vehicles to comply with either a four-tire,
25 percent option, which essentially would have required manufacturers
to install direct TPMSs or improved indirect TPMSs, or a one-tire, 30
percent option, which would have permitted manufacturers to install
either direct TPMSs or any type of indirect TPMSs, including current
indirect TPMSs. For the long-term, the period beginning November 1,
2006, the requirements of the four-tire, 25 percent option would have
become mandatory for all vehicles subject to the TPMS standard.
---------------------------------------------------------------------------
\13\ The rationales for the provisions of that draft final rule
are discussed below in section VI.A., ``Summary of Preliminary
Determination about the Final Rule.''
---------------------------------------------------------------------------
As explained further below in section V.A. ``Alternative Long-Term
Requirements Analyzed in Making Preliminary Determination,'' NHTSA
analyzed three alternatives for the long term requirement in developing
the draft final rule: a four-tire, 20 percent alternative, a three-
tire, 25 percent alternative, and a four-tire, 25 percent alternative.
F. OMB Return Letter
After reviewing the draft final rule, OMB returned it to NHTSA for
reconsideration, with a letter explaining its reasons for doing so, on
February 12, 2002.\14\
---------------------------------------------------------------------------
\14\ A copy of the return letter has been placed in the docket
(Docket No. NHTSA-2000-8572-202). The letter also is available
electronically at www.whitehouse.gov/omb/inforeg/
dot_revised_tire_rtnltr.pdf.
---------------------------------------------------------------------------
In the letter, OMB stated its belief that the draft final rule and
accompanying regulatory impact analysis did not adequately demonstrate
that the agency had selected the best available method of improving
overall vehicle safety. OMB said further that: NHTSA should base its
decision about the final rule on overall vehicle safety, instead of
just tire safety; while direct TPMSs can detect under-inflation under a
greater variety of circumstances than indirect TPMSs, the indirect
system captures a substantial portion of the benefit provided by direct
systems; NHTSA should consider a fourth alternative for the long-term
requirement, a one-tire, 30 percent compliance option, indefinitely,
since it would allow vehicle manufacturers to install current indirect
TPMSs; NHTSA, in analyzing long-term alternatives, should consider both
their impact on the availability of ABS as well as the potential safety
benefits of ABS; and that NHTSA should provide a better explanation of
the technical foundation for the agency's safety benefits estimates and
subject those estimates to sensitivity analyses.
G. Public Comments on OMB's Return Letter
Consumers Union (CU) and Public Citizen (PC) submitted comments on
the OMB return letter.\15\
---------------------------------------------------------------------------
\15\ Both letters have been placed in the docket. The CU letter
is Docket No. NHTSA-2000-8572-204, and the PC letter is Docket No.
NHTSA-2000-8572-199.
---------------------------------------------------------------------------
CU stated that direct TPMSs offer significant safety advantages
over indirect TPMSs. CU recently performed tire air leakage testing and
found that all four tires on a vehicle will likely lose pressure at a
similar rate.\16\ CU said that direct TPMSs could detect such pressure
losses, while indirect TPMSs could not.
---------------------------------------------------------------------------
\16\ CU tested three samples of 36 tire models over a six-month
period. CU mounted the tires on new rims and inflated the tires to
30 psi. Then CU stored the tires indoors at room temperature for six
months and checked their inflation pressure each month. After six
months, the average pressure loss was about 4.4 psi. A copy of CU's
test procedures and the test results has been placed in the docket.
(Docket No. NHTSA-2000-8572-203.)
---------------------------------------------------------------------------
CU questioned OMB's returning the TPMS final rule and asking NHTSA
to consider the potential benefits of ABS in making a final decision on
TPMS requirements. CU stated:
We cannot understand the logic of delaying an important safety
measure like direct tire pressure monitoring systems while NHTSA
studies issues related to a less effective alternative because that
alternative might encourage automakers to make ABS more widely
available.
Finally, CU stated that, while Congress mandated that NHTSA issue a
regulation for TPMSs, Congress did not mandate that the agency issue a
regulation requiring ABS to be installed in all vehicles.
PC also supported the four-tire, 20 percent alternative. PC argued
that indirect TPMSs have shortcomings, including:
They can detect under-inflation only if one tire is more
than 25 percent less inflated than the other tires.
They cannot detect when all four tires are equally under-
inflated, a likely scenario if the tires are purchased or checked at
the same time.
They also cannot detect when two tires on the same side of
the vehicle or the same axle are under-inflated, but can detect when
diagonal tires are under-inflated.
PC also objected to OMB's returning the TPMS final rule and asking
NHTSA to consider the potential benefits of ABS in making a final
decision on TPMS requirements. PC questioned OMB's return letter,
arguing that it employs
unproven assumptions about the cost and market effects of
combining indirect systems with a requirement for anti-lock brakes
(ABS) (a long-controversial area outside the focus of the agency's
current rulemaking mandate), which, in turn, has only statistically
insignificant and highly disputed safety effects.
PC also questioned the potential benefits of ABS cited by OMB. In
response to OMB's reliance on a study by Charles Farmer, the PC
asserted that Mr. Farmer
found that ABS had no statistically significant effect on crash
fatalities. [Emphasis original.] Farmer was unable to determine
whether ABS ultimately saved or cost lives across the vehicle fleet,
making the ``between 4 and 9 percent reduction'' in crash fatalities
[cited in the OMB letter] a statistical blip that may actually be
zero percent.
H. Congressional Hearing
On February 28, 2002, the House Committee on Energy and Commerce
held an oversight hearing on the implementation of the TREAD Act.
During the hearing, several Congressmen discussed their expectations
for the TPMS rulemaking. Expressing concern about the cumulative damage
done to a tire that is run while under-inflated, Congressman Tom Sawyer
asked whether a warning threshold of 25 percent below placard pressure
was low enough. Given the potential for catastrophic failure of tires
run too long while under-inflated, the Congressman stated that it was
important that the TPMS not encourage drivers to drive on under-
inflated tires.
Congressman Markey, the sponsor of the amendment that added the
TPMS mandate to the TREAD Act, indicated that the reliance of drivers
on the TPMS warning light could lead to safety problems if the TPMS
does not provide sufficient warnings. He acknowledged that, during the
consideration of the TPMS amendment, he had mentioned a TPMS that was
then in use (an ABS-based TPMS on the Toyota Sienna). He said that
while any TPMS was acceptable during the initial implementation period
for the TPMS requirements, the real intent of the amendment is to
provide a warning in all instances.
III. Safety Problem
Many vehicles have significantly under-inflated tires, primarily
because drivers infrequently check their
[[Page 38713]]
vehicles' tire pressure. Other contributing factors are the difficulty
of visually detecting when a tire is significantly under-inflated and
the loss of tire pressure due to natural leakage and seasonal climatic
changes.
A. Infrequent Driver Monitoring of Tire Pressure
Surveys have shown that most drivers check the inflation pressure
in their vehicles' tires infrequently. For example, in September 2000,
the Bureau of Transportation Statistics (BTS) conducted an omnibus
survey for NHTSA. One of the questions posed was: ``How often do you,
or the person who checks your tires, check the air pressure in your
tires?'' The answers indicated that 29 percent of the respondents
stated that they check the air pressure in their tires monthly; another
29 percent stated that they check the air pressure only when one or
more of their vehicle's tires appears under-inflated; 19 percent stated
that they only have the air pressure checked when the vehicle is
serviced; 5 percent stated that they only check the air pressure before
taking their vehicle on a long trip; and 17 percent stated that they
check the air pressure on some other occasion. Thus, 71 percent of the
respondents stated that they check the air pressure in the vehicles'
tires less than once a month.\17\
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\17\ The agency notes that it seems likely that the respondents
in both of the surveys cited overstated the frequency with which
they check tire pressure, particularly given the fact that these
surveys were conducted during the height of publicity about tire
failures on sport utility vehicles in the late 2000 and early 2001.
---------------------------------------------------------------------------
In addition, NHTSA's National Center for Statistics and Analysis
(NCSA) conducted a survey in February 2001. The survey was designed to
assess the extent to which passenger vehicle drivers are aware of the
recommended air pressure for their vehicles' tires, if drivers monitor
air pressure, and to what extent actual tire pressure differs from
placard pressure.
Data was collected through the infrastructure of the National
Accident Sampling System--Crashworthiness Data System (NASS-CDS). The
NASS-CDS consists of 24 Primary Sampling Units (PSUs) located across
the country. Within each PSU, a random selection of zip codes was
obtained from a list of eligible zip codes. Within each zip code, a
random selection of two gas stations was obtained.
A total of 11,530 vehicles were inspected at these gas stations.
This total comprised 6,442 passenger cars, 1,874 sports utility
vehicles (SUVs), 1,376 vans, and 1,838 pick-up trucks. For analytical
purposes, the data were divided into three categories: (1) Passenger
cars; (2) pick-up trucks, SUVs, and vans with P-metric tires; and (3)
pick-up trucks, SUVs, and vans with either light truck (LT) or
flotation tires.
Drivers were asked how often they normally check their tires to
determine if they are properly inflated. Their answers are in the
following table:
------------------------------------------------------------------------
Drivers of pick-up
trucks, SUVs, and vans
Drivers of (%)
How often is tire pressure passenger -------------------------
checked? cars (%) LT or
P-metric flotation
tires tires
------------------------------------------------------------------------
Weekly........................... 8.76 8.69 8.16
Monthly.......................... 21.42 25.19 39.88
When they seem low............... 25.63 23.58 15.59
When serviced.................... 30.18 27.72 25.54
For long trip.................... 0.99 2.39 2.17
Other............................ 6.46 8.27 6.97
Do not check..................... 6.56 4.16 1.69
------------------------------------------------------------------------
These data indicate that only about 30 percent of drivers of
passenger cars, 34 percent of drivers of pick-up trucks, SUVs, and vans
with P-metric tires, and 48 percent of drivers of pick-up trucks, SUVs,
and vans with either LT or flotation tires claim that they check the
air pressure in their vehicles' tires at least once a month.
B. Loss of Tire Pressure Due to Natural and Other Causes
According to data from the tire industry, 85 percent of all tire
air pressure losses are the result of slow leaks that occur over a
period of hours, days, or months. Only 15 percent are rapid air losses
caused by contact with a road hazard, e.g., when a large nail that does
not end up stuck in the tire punctures a tire.
Slow leaks may be caused by many factors. Tire manufacturers
commented that tires typically lose air pressure through natural
leakage and permeation at a rate of about 1 psi per month. Testing by
CU supports those comments. In addition, tire manufacturers said that
seasonal climatic changes result in air pressure losses on the order of
1 psi for every 10 degree F decrease in the ambient temperature. Slow
leaks also may be caused by slight damage to a tire, such as a road
hazard that punctures a small hole in the tire or a nail that sticks in
the tire. NHTSA has no data indicating how often any of these causes
results in a slow leak.
C. Percentage of Motor Vehicles With Under-Inflated Tires
During the February 2001 survey, NASS-CDS crash investigators
measured tire pressure on each vehicle coming into the gas station and
compared the measured pressures to the vehicle's placard pressure. They
found that about 36 percent of passenger cars and about 40 percent of
light trucks had at least one tire that was at least 20 percent below
the placard pressure.\18\ About 26 percent of passenger cars and 29
percent of light trucks had at least one tire that was at least 25
percent below the placard pressure. The agency notes those levels of
under-inflation because they are the threshold levels for the low-tire
pressure warning telltale illumination under the two alternatives the
agency proposed in the NPRM for TPMSs. (66 FR 38982, July 26, 2001).
---------------------------------------------------------------------------
\18\ For purposes of this discussion, the agency classified
pick-up trucks, SUVs, and vans with either P-metric, LT, or
flotation tires as light trucks.
---------------------------------------------------------------------------
D. Consequences of Under-Inflation of Tires
1. Reduced Vehicle Safety--Tire Failures and Increases in Stopping
Distance
When a tire is used while significantly under-inflated, its
sidewalls flex more and the air temperature inside the tire increases,
increasing stress and the risk of failure. In addition, a significantly
under-inflated tire loses lateral traction,
[[Page 38714]]
making handling more difficult. Under-inflation also plays a role in
crashes due to flat tires and blowouts. Finally, significantly under-
inflated tires can increase a vehicle's stopping distance.
NHTSA's current crash files do not contain any direct evidence that
points to low tire pressure as the cause of any particular crash.\19\
However, this lack of data does not imply that low tire pressure does
not cause or contribute to any crashes. The agency believes that it
simply reflects the fact that measurements of tire pressure are not
among the vehicle information included in the crash reports received by
the agency and placed in its crash data bases.\20\
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\19\ In response to the TREAD Act, NHTSA has added new tire
related variables and attributes, including tire make, model,
recommended tire pressure, actual tire pressure, and tread depth to
its crash databases. These new variables will provide more specific
tire data for vehicles involved in crashes.
\20\ These crash databases are the NASS-CDS and the Fatality
Analysis Reporting System (FARS).
---------------------------------------------------------------------------
The only tire-related data element in the agency's crash databases
is ``flat tire or blowout.'' However, even in crashes for which a flat
tire or blowout is reported, crash investigators cannot tell whether
low tire pressure contributed to the tire failure.
The agency examined its crash files to gather information on tire-
related problems that resulted in crashes. The NASS-CDS has trained
investigators who collect data on a sample of tow-away crashes around
the United States. These data can be weighted to generate national
estimates.
The NASS-CDS General Vehicle Form contains a value indicating
vehicle loss of control due to a blowout or flat tire. This value is
used only when a vehicle's tire went flat, causing a loss of control of
the vehicle and a crash. The value is not used for cases in which one
or more of a vehicle's tires were under-inflated, preventing the
vehicle from performing as well as it could have in an emergency
situation.
NHTSA examined NASS-CDS data for 1995 through 1998 and estimated
that 23,464 tow-away crashes, or 0.5 percent of all crashes, are caused
by blowouts or flat tires each year. The agency placed the tow-away
crashes from the NASS-CDS files into two categories: passenger car
crashes and light truck crashes. Passenger cars were involved in 10,170
of the tow-away crashes caused by blowouts or flat tires, and light
trucks were involved in the other 13,294.
NHTSA also examined data from the Fatality Analysis Reporting
System (FARS) for evidence of tire problems in fatal crashes. In FARS,
if tire problems are noted after the crash, the simple fact of their
existence is all that is noted. No attempt is made to ascribe a role in
the crash to those problems. Thus, the agency does not know whether the
noted tire problem caused the crash, influenced the severity of the
crash, or simply occurred during the crash. For example, a tire may
have blown out and caused the crash, or it may have blown out during
the crash when the vehicle struck some object, such as a curb.
Thus, while an indication of a tire problem in the FARS file gives
some clue as to the potential magnitude of tire problems in fatal
crashes, the FARS data cannot give a precise measure of the causal role
played by those problems. The very existence of tire problems is
sometimes difficult to detect and code accurately. Further, coding
practices vary from State to State. Nevertheless, the agency notes
that, from 1995 to 1998, 1.1 percent of all light vehicles involved in
fatal crashes were coded as having tire problems. Over 535 fatal
crashes involved vehicles coded with tire problems.
Under-inflated tires can contribute to types of crashes other than
those resulting from blowouts or tire failure, including crashes which
result from: skidding and/or a loss of control of the vehicle in a
curve or in a lane change maneuver; an increase in a vehicle's stopping
distance; or hydroplaning on a wet surface.
The 1977 Indiana Tri-level study associated low tire pressure with
loss of control on both wet and dry pavements. The study never defined
low tire pressure as a ``definite'' (i.e., 95 percent certainty that
the crash would not have occurred absent this condition) cause of any
crash, but did identify it as a ``probable'' (80 percent certainty that
the crash would not have occurred absent this condition) cause of the
crash in 1.4 percent of the 420 in-depth crash investigations.
The study divided ``probable'' cause into two levels: a ``causal''
factor and a ``severity-increasing'' factor. A ``causal'' factor was
defined as a factor whose absence would have prevented the accident
from occurring. A ``severity-increasing'' factor was defined as a
factor whose presence was not sufficient, by itself, to result in the
occurrence of the accident, but which resulted in an increase in speed
of the initial impact. The study determined that under-inflated tires
were a causal factor in 1.2 percent of the probable cause cases and a
severity-increasing factor in 0.2 percent of the probable cause cases.
Note that more than one probable cause could be assigned to a
crash. In fact, there were a total of 138.8 percent causes listed as
probable causes (92.4 percent human factors, 33.8 percent environmental
factors, and 12.6 percent vehicle factors). Thus, tire under-
inflation's part of the total is one percent (1.4/138.8). The agency
focused solely on the probable cause cases, which represent 0.86
percent of crashes (1.2/1.4 * 1.0).
Tires are designed to maximize their performance capabilities at a
specific inflation pressure. When a tire is under-inflated, the shape
of its footprint and the pressure it exerts on the road surface are
both altered, especially on wet surfaces. An under-inflated tire has a
larger footprint than a properly inflated tire. Although the larger
footprint results in an increase in rolling resistance on dry road
surfaces due to increased friction between the tire and the road
surface, it also reduces the tire load per unit area. On dry road
surfaces, the countervailing effects of a larger footprint and reduced
load per unit of area nearly offset each other, with the result that
the vehicle's stopping distance performance is only mildly affected by
under-inflation.
On wet surfaces, however, under-inflation typically increases
stopping distance for several reasons. First, as noted above, the
larger tire footprint provides less tire load per area than a smaller
footprint. Second, since the limits of adhesion are lower and achieved
earlier on a wet surface than on a dry surface, a tire with a larger
footprint, given the same load, is likely to slide earlier than the
same tire with a smaller footprint because of the lower load per
footprint area. The rolling resistance of an under-inflated tire on a
wet surface is greater than the rolling resistance of the same tire
properly-inflated on the same wet surface. This is because the slightly
larger tire footprint on the under-inflated tire results in more rubber
on the road and hence more friction to overcome. However, the rolling
resistance of an under-inflated tire on a wet surface is less than the
rolling resistance of the same under-inflated tire on a dry surface
because of the reduced friction caused by the thin film of water
between the tire and the road surface. The less tire load per area and
lower limits of adhesion of an under-inflated tire on a wet surface are
enough to overcome the increased friction caused by the larger
footprint of the under-inflated tire. Hence, under-inflated tires cause
longer stopping distance on wet surfaces than properly-inflated tires.
[[Page 38715]]
The agency has received data from Goodyear indicating that
significantly under-inflated tires increase a vehicle's stopping
distance.\21\ The effects of tire under-inflation on vehicle stopping
distance are discussed in greater detail in the agency's Final Economic
Analysis (FEA).
---------------------------------------------------------------------------
\21\ Goodyear submitted these data to the docket in a letter
dated September 14, 2001. See Docket No. NHTSA-2000-8572-160. OMB
criticized NHTSA's application of these data to certain vehicle
types in estimating safety benefits for this rulemaking. The agency
responds to that criticism below in section VI.F., ``Technical
Foundation for NHTSA's Safety Benefit Analyses.'' The Alliance also
questioned NHTSA's use of the Goodyear data. The agency explains its
use of the Goodyear data below in footnotes 22 and 23, and in the
agency's Final Economic Analysis (FEA).
---------------------------------------------------------------------------
As explained in the FEA, the agency did not use the VRTC data or
the Goodyear data that the agency used to estimate benefits in the NPRM
because of concerns with the way in which the both tests were
performed.\22\ The agency believes that the more recent Goodyear test
methodology adequately addressed these concerns.\23\
---------------------------------------------------------------------------
\22\ For example, the VRTC only tested new tires, not worn tires
that are more typical of the tires on most vehicles. In addition,
the NHTSA track surface is considered to be aggressive in that it
allows for maximum friction with tire surfaces. It is more
representative of a new road surface than the worn surfaces
experienced by the vast majority of road traffic. The previous
Goodyear tests on wet surfaces were conducted on surfaces with .05
inch of standing water. This is more than would typically be
encountered under normal wet road driving conditions. The agency
expressed concerns with the adequacy of both sets of test data in a
memo to the docket. (Docket No. NHTSA-2000-8572-81.)
\23\ For example, in its more recent tests Goodyear tested tires
with two tread depths: full tread, which is representative of new
tires, and half tread, which is representative of worn tires.
Goodyear also conducted wet surface tests on surfaces with .02 inch
of standing water, which is more representative of typical wet road
driving conditions.
---------------------------------------------------------------------------
2. Reduced Tread Life
Unpublished data submitted to the agency by Goodyear indicate that
when a tire is under-inflated, more pressure is placed on the shoulders
of the tire, causing the tread to wear incorrectly.\24\ The Goodyear
data also indicate that the tread on an under-inflated tire wears more
rapidly than it would if the tire were inflated to the proper pressure.
---------------------------------------------------------------------------
\24\ Docket No. NHTSA-2000-8572-26.
---------------------------------------------------------------------------
The Goodyear data indicate that the average tread life of a tire is
45,000 miles, and the average cost of a tire is $61 (in 2000 dollars).
Goodyear also estimated that a tire's average tread life would drop to
68 percent of the expected tread life if tire pressure dropped from 35
psi to 17 psi and remained there. Goodyear assumed that this
relationship was linear. Thus, for every 1-psi drop in tire pressure,
tread life would decrease by 1.78 percent (32 percent/18 psi). This
loss of tread life would take place over the lifetime of the tire.
Thus, according to Goodyear's data, if the tire remained under-inflated
by 1 psi over its lifetime, its tread life would decrease by about 800
miles (1.78 percent of 45,000 miles).
As noted above, data from the NCSA tire pressure survey indicate
that 26 percent of passenger cars had at least one tire that was under-
inflated by at least 25 percent. The average level of under-inflation
of the four tires on passenger cars with at least one tire under-
inflated by at least 25 percent was 6.8 psi. Thus, on average, these
passenger cars could lose about 5,440 miles (6.8 psi under-inflation x
800 miles) of tread life due to under-inflation, if their tires were
under-inflated to that extent throughout the life of the tires.
Also as noted above, data from the NCSA tire pressure survey
indicate that about 29 percent of light trucks had at least one tire
that was under-inflated by at least 25 percent. The average level of
under-inflation of the four tires on light trucks with at least one
tire under-inflated by at least 25 percent was 8.7 psi. Thus, on
average, these light trucks could lose about 6,960 miles (8.7 psi
under-inflation x 800 miles) of tread life due to under-inflation, if
their tires were under-inflated to that extent throughout the life of
the tires.
3. Reduced Fuel Economy
Under-inflation increases the rolling resistance of a vehicle's
tires and, correspondingly, decreases the vehicle's fuel economy.
According to a 1978 report, fuel efficiency is reduced by one percent
for every 3.3 psi of under-inflation.\25\ More recent data provided by
Goodyear indicate that fuel efficiency is reduced by one percent for
every 2.96 psi of under-inflation.\26\
---------------------------------------------------------------------------
\25\ The Aerospace Corporation, Evaluation of Techniques for
Reducing In-use Automotive Fuel Consumption, June 1978.
\26\ Docket No. NHTSA-2000-8572-26.
---------------------------------------------------------------------------
NHTSA notes that there is an apparent conflict between these data,
which indicate that under-inflation increases rolling resistance and
thus decreases fuel economy and the previously mentioned Goodyear data
that indicates under-inflated tires increase a vehicle's stopping
distance. While an under-inflated tire typically has a larger tread
surface area (i.e., tire footprint) in contact with the road, which
might be thought to improve its traction during braking, the larger
tire footprint also reduces the tire load per unit area. The larger
footprint does result in an increase in rolling resistance on dry road
surfaces due to increased friction between the tire and the road
surface. On dry road surfaces, though, the countervailing effects of a
larger footprint and reduced load per unit of area nearly offset each
other, with the result that the vehicle's stopping distance performance
is only mildly affected by under-inflation on those surfaces. However,
as explained above in section III.D.1., ``Reduced Vehicle Safety--Tire
Failures and Increases in Stopping Distance,'' on wet surfaces other
attributes of under-inflation lead to increased stopping distances.
IV. Tire Pressure Monitoring Systems
There are currently two types of TPMSs: direct and indirect. Other
types, including hybrid TPMSs that combine aspects of both direct and
indirect systems, may be developed in the future. Direct TPMSs directly
measure the pressure in a vehicle's tires, while indirect TPMSs
estimate differences in pressure by comparing the rotational speed of
the wheels. To varying degrees, both types can inform the driver when
the pressure in one or more tires falls below a pre-determined level.
Unless the TPMS is connected to an automatic inflation system, the
driver must stop the vehicle and inflate the under-inflated tire(s),
preferably to the pressure recommended by the vehicle manufacturer.
Currently, TPMSs are available as original equipment on a few vehicle
models. They are available also as after-market equipment, but few are
sold. At this time, NHTSA does not have any information indicating that
a hybrid TPMS is being planned for production. However, the agency
received comments from TRW, a TPMS manufacturer, stating its belief
that such a system could be produced.
The VRTC evaluated six direct and four indirect TPMSs that are
currently available.\27\ The VRTC found that the direct TPMSs were
accurate to within an average of 1.0 psi.\28\ This leads
the agency to believe that those current TPMSs are more accurate than
the systems that were available at the time of the agency s 1981
rulemaking on TPMSs.
---------------------------------------------------------------------------
\27\ An Evaluation of Existing Tire Pressure Monitoring Systems,
May 2001. A copy of this report is available in the docket. (Docket
No. NHTSA-2000-8572-29.)
\28\ This is not to say that the systems were able to detect a
1.0 psi drop in pressure. The systems were accurate within
1.0 psi once tire pressure had fallen by a certain
percentage.
---------------------------------------------------------------------------
Following is a description of the two currently available types of
TPMSs and their capabilities.
[[Page 38716]]
A. Indirect TPMSs
Current indirect TPMSs work with a vehicle's ABS. The ABS employs
wheel speed sensors to measure the rotational speed of each of the four
wheels. As a tire's pressure decreases, the rolling radius decreases,
and the rotational speed of that wheel increases correspondingly. Most
current indirect TPMSs compare the sums of the wheel speeds on each
diagonal (i.e., the sum of the speeds of the right front and left rear
wheels as compared to the sum of the speeds of the left front and right
rear wheels). Dividing the difference of the sums by the average of the
four wheels speeds allows the indirect TPMS to have a ratio that is
independent of vehicle speed. This ratio is best expressed by the
following equation: [(RF + LR) - (LF + RR)/Average Speed]. If this
ratio deviates from a set tolerance, one or more tires must be over- or
under-inflated. A telltale then indicates to the driver that a tire is
under-inflated. However, the telltale cannot identify which tire is
under-inflated. Current vehicles that have indirect TPMSs include the
Toyota Sienna, Ford Windstar, and Oldsmobile Alero.
Current indirect TPMSs must compare the average of the speeds of
the diagonal wheels for several reasons. First, current indirect TPMSs
cannot compare the speed of one wheel to the speeds of the other three
wheels individually or to the average speed of the four wheels. During
any degree of turning, the outside tires must rotate faster than the
inside tires. Thus, all four wheel speeds deviate significantly when
the vehicle is in a curve or turn. If a current indirect TPMS compared
each individual wheel speed to the average of all four wheels speeds,
the system would provide a false alarm each time the vehicle rounded a
curve or made a turn. The same would be true if the indirect TPMS
compared each individual wheel speed to the speed of the other three
wheels individually. Since the outside wheels would rotate much faster
than the inside wheels in a curve or turn, each outside tire would
appear to be under-inflated when compared to an inside tire.
Current indirect TPMSs also cannot compare the speeds of the front
wheels to the speeds of the rear wheels because in curves, the front
and rear wheels (on both sides of the vehicle) rotate at different
speeds. This is primarily due to the fact that the front axle is
steerable and follows a different trajectory than the rear axle. As a
result, current indirect TPMS must compare a tire from each side and a
tire from the front and rear axles to factor out the speed difference
caused by curves and turns. Thus, current indirect TPMSs must compare
the average speed of the diagonal wheels.
The VRTC tested four current ABS-based indirect TPMSs. None met all
the requirements of either alternative proposed in the NPRM. All but
one did not illuminate the low tire pressure warning telltale when the
pressure in the vehicle's tires decreased to 20 or 25 percent below the
placard pressure.\29\ The VRTC determined that since reductions in tire
diameter with reductions in pressure are very slight in the 15-40 psi
range, most current indirect TPMSs require a 20 to 30 percent drop in
pressure before they are able to detect under-inflation. The VRTC also
concluded that those thresholds were highly dependent on tire and
loading factors.
---------------------------------------------------------------------------
\29\ The Continental Teves indirect TPMS on the BMW M3 activated
the warning telltale at pressures between 9 and 21 percent below the
placard pressure.
---------------------------------------------------------------------------
The VRTC also found that none of the tested indirect TPMSs were
able to detect significant under-inflation when all four of the
vehicle's tires were equally under-inflated, or when two tires on the
same axle or two tires on the same side of the vehicle were equally
under-inflated. However, the VRTC did find that indirect TPMSs could
detect when two tires located diagonally from each other (e.g., the
front left and back right tires) became significantly under-inflated.
B. Direct TPMSs
Direct TPMSs use pressure sensors, located in each wheel, to
directly measure the pressure in each tire. These sensors broadcast
pressure data via a wireless radio frequency transmitter to a central
receiver. The data are then analyzed and the results sent to a display
mounted inside the vehicle. The type of display varies from a simple
telltale, which is how most vehicles are currently equipped, to a
display showing the pressure in each tire, sometimes including the
spare tire. Thus, direct TPMSs can be linked to a display that tells
the driver which tire is under-inflated. An example of a vehicle
equipped with a direct system is the Chevrolet Corvette.
Since direct TPMSs actually measure the pressure in each tire, they
are able to detect when any tire or when each tire in any combination
of tires is under-inflated, including when all four of the vehicle's
tires are equally under-inflated. Direct TPMSs also can detect small
pressure losses. Some systems can detect a drop in pressure as small as
1 psi.
C. Hybrid TPMSs
In their comments on the NPRM, TRW, a manufacturer of both direct
and indirect TPMSs, stated that in order to meet the proposed
requirements of the 3-tire, 25 percent alternative, current indirect
TPMSs would need the equivalent of the addition of two tire pressure
sensors and a radio frequency receiver. The tire pressure sensors would
be installed on wheels located diagonally from each other.
For the following reasons, the agency believes that such a
``hybrid'' TPMS would be able to overcome the limitations of current
indirect TPMSs, i.e., the inability to detect when all four tires, or
two tires on the same axle or same side of the vehicle are under-
inflated. First, a hybrid TPMS would be able to detect when two tires
on the same axle or the same side of the vehicle were under-inflated
because one of those tires necessarily would contain a direct pressure
sensor. Second, a hybrid TPMS would be able to detect when the two
tires without a direct pressure sensor were under-inflated because they
would be located diagonally from each other, and, as the VRTC found in
its review of current TPMSs, current indirect TPMSs are able to detect
when two tires located diagonally from each other are under-inflated.
Third, a hybrid TPMS would be able to detect when three or four tires
were under-inflated because one of those tires necessarily would
contain a direct pressure sensor.
However, since the agency does not have any information indicating
that a hybrid TPMS is currently being planned for production, the
agency does not know when such a system could be produced.
V. Summary of Preliminary Determination About the Final Rule
In this section, NHTSA summarizes its preliminary determination
about the final rule that was submitted to OMB in December 2001.
A. Alternative Long-Term Requirements Analyzed in Making Preliminary
Determination
For purposes of the preliminary determination, the agency analyzed
three alternatives. The first alternative (four tires, 20 percent)
would have required a vehicle's TPMS to warn the driver when the
pressure in any single tire or in each tire in any combination of
tires, up to a total of four tires, fell to 20 percent or more below
the placard pressure, or a minimum level of pressure specified in the
standard, whichever pressure was higher. The
[[Page 38717]]
second alternative (three tires, 25 percent) would have required a
vehicle's TPMS to warn the driver when the pressure in any single tire
or in each tire in any combination of tires, up to a total of three
tires, fell to 25 percent or more below the placard pressure, or a
minimum level of pressure specified in the standard, whichever pressure
was higher. The third alternative (four tires, 25 percent) combined
aspects of the first two alternatives. It would have required a
vehicle's TPMS to warn the driver when the pressure in any single tire
or in each tire in any combination of tires, up to a total of four
tires, fell to 25 percent or more below the placard pressure, or a
minimum level of pressure specified in the standard, whichever pressure
was higher. The minimum levels of pressure specified in the standard
would have been the same for all three alternatives.
The agency estimated that the four-tire, 20 percent alternative
would have prevented from 141 to 145 fatalities and prevented or
reduced in severity from 10,271 to 10,611 injuries per year.\30\ The
agency estimated that the average net cost of this alternative would
have been from $76.77 to $77.53 per vehicle.\31\ Since approximately 16
million vehicles are produced for sale in the United States each year,
the total annual net cost of this alternative would have been from
$1.228 billion to $1.241 billion. The net cost per equivalent life
saved would have been from $5.1 million to $5.3 million.
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\30\ NHTSA assumed that drivers would respond differently to
different information displays. To get the upper bound, the agency
assumed that manufacturers that installed direct TPMSs would also
install a display showing the pressure of each tire. Currently only
direct TPMSs are capable of displaying individual tire pressure. The
agency also assumed that 33 percent of drivers would respond to such
a display by re-inflating their tires when they became under-
inflated by 10 percent, and that the other 67 percent would respond
by re-inflating their tires when they became under-inflated by 20
percent, i.e., when the warning telltale would have been activated.
To get the lower bound, the agency assumed that manufacturers would
install only a low tire pressure warning telltale, as would have
been required. Thus, all drivers would not re-inflate their tires
until they became under-inflated by 20 percent, and the warning
telltale was activated.
\31\ The net cost is the vehicle cost plus the maintenance cost
minus the fuel and tread wear savings. The difference in costs is
due to the cost of adding an individual tire pressure display. The
agency assumed that manufacturers would install direct TPMSs on
vehicles that are not equipped with ABS because the cost of adding a
direct TPMS was significantly less than the cost of adding ABS and
an indirect TPMS.
---------------------------------------------------------------------------
The agency estimated that the three-tire, 25 percent alternative
would have prevented 110 fatalities and prevented or reduced in
severity 7,526 injuries per year. The agency estimated that the average
net cost would have been $63.64 per vehicle, and the total annual net
cost would have been $1.018 billion. The net cost per equivalent life
saved would have been $5.8 million.
The agency estimated that the four-tire, 25 percent alternative
would have prevented 124 fatalities and prevented or reduced in
severity 8,722 injuries per year. The agency estimated that the average
net cost would have been $53.87 per vehicle, and the total annual net
cost would have been $862 million. The net cost per equivalent life
saved would have been $4.3 million.
The agency noted that the vehicle costs of these alternatives could
be reduced in the future as manufacturers learned how to produce TPMSs
more efficiently. Moreover, maintenance costs could be significantly
reduced in the future if manufacturers could mass produce a direct TPMS
that did not require the pressure sensors to be replaced when the
batteries are depleted.\32\
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\32\ One TPMS manufacturer, IQ-mobil Electronics of Germany,
indicated in its comments that it has developed a pressure sensor
that does not require a battery.
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NHTSA considered these three alternatives because the agency
believed that TPMSs that complied with these alternatives would warn
drivers of significantly under-inflated tires in a wide variety of
reasonably foreseeable circumstances, including when more than one tire
was significantly under-inflated. The agency also believed that
improved indirect TPMSs could be developed to meet the requirements of
the three-tire, 25 percent alternative and hybrid TPMSs could be
developed to meet the three-tire, 25 percent and four-tire, 25 percent
alternatives. Thus, the agency believed that these alternatives would
provide an effective warning while striking a reasonable balance
between encouraging further improvements in TPMS technology and
stringency of the performance requirements and striking a reasonable
balance between safety benefits and costs.
B. Phase-In and Long-Term Requirements
To facilitate compliance, the preliminary determination specified a
four-year phase-in schedule,\33\ During the phase-in, i.e., between
November 1, 2003 and October 31, 2006, it would have allowed compliance
with either of two options: a four-tire, 25 percent option or a one-
tire, 30 percent option. Under the first option, a vehicle's TPMS would
have had to warn the driver when the pressure in one or more of the
vehicle's tires, up to a total of four tires, was 25 percent or more
below the placard pressure, or a minimum level of pressure specified in
the standard, whichever pressure was higher. Under the second option, a
vehicle's TPMS would have had to warn the driver when the pressure in
any one of the vehicle's tires was 30 percent or more below the placard
pressure, or a minimum level of pressure specified in the standard,
whichever pressure was higher. The minimum levels of pressure specified
in the standard were the same for both compliance options.
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\33\ The phase-in schedule was as follows: 10 percent of a
manufacturer's affected vehicles would have had to comply with
either compliance option in the first year; 35 percent in the second
year; and 65 percent in the third year. In the fourth year, 100
percent of a manufacturer's affected vehicles would have had to
comply with the long-term requirements, i.e., the four-tire, 25
percent compliance option.
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Under both options, the preliminary determination would have
required the low tire pressure warning telltale to remain illuminated
as long as any one of the vehicle's tires remained significantly under-
inflated, and the key locking system was in the ``On'' (``Run'')
position. The telltale could have been deactivated automatically only
when all of the vehicle's tires ceased to be significantly under-
inflated, or manually in accordance with the vehicle manufacturer's
instructions.
The preliminary determination would have required each TPMS to be
compatible with all replacement or optional tires (but not rims) of the
size(s) recommended for use on the vehicle by the vehicle manufacturer.
It would also have required that the telltale perform a bulb-check at
vehicle start-up. It specified written instructions explaining the
purpose of the low tire pressure warning telltale, the potential
consequences of significantly under-inflated tires, the meaning of the
telltale when it was illuminated, and what actions drivers should take
when the telltale is illuminated, to be placed in the vehicle's owner's
manual.
The preliminary determination would not have required TPMSs to
monitor the spare tire, either when the tire was stowed or when it was
installed on the vehicle. It also would not have required the TPMS to
indicate a system malfunction.
The agency created the one-tire, 30 percent option so that vehicle
manufacturers could continue to install current indirect TPMSs for
several more years, thus providing additional time and flexibility for
innovation and technological development. The agency created the other
option by adjusting the definition of ``significantly under-inflated''
for the four-tire option to 25 percent (instead of 20 percent) so that
[[Page 38718]]
improved indirect TPMSs and hybrid TPMSs could be used to comply with
the TPMS standard. After the phase-in, i.e., after October 31, 2006,
the second option would have been terminated, and the provisions of the
first option would have become mandatory for all new vehicles.
The agency tentatively believed that a four-tire, 25 percent
requirement was preferable for the long-term because it would require
TPMSs that warn drivers about all combinations of significantly under-
inflated tires and provide more timely and effective warnings. The
agency tentatively believed that a one-tire, 30 percent requirement
would allow TPMSs that do not warn about all combinations of
significantly under-inflated tires and do not provide warnings until
the extent of under-inflation reaches 30 percent below the placard
pressure. Thus, it appeared that a four-tire, 25 percent requirement
would better fulfill the purposes of the TPMS mandate in the TREAD Act,
while encouraging further improvements in TPMS technology.
VI. Response to Issues Raised in OMB Return Letter About
Preliminary Determination
Pursuant to section 6(a)(3) of Executive Order 12866, NHTSA is
required to provide a written response to the points made by OMB in its
February 12 return letter. As noted above, OMB stated in its return
letter that: NHTSA should base its decision about the final rule on
overall safety, instead of tire safety; while direct TPMSs can detect
under-inflation under a greater variety of circumstances than indirect
TPMSs, the indirect system captures a substantial portion of the
benefit provided by direct systems; NHTSA should consider a fourth
alternative for the long-term requirement, a one-tire, 30 percent
compliance option, indefinitely, since it would allow vehicle
manufacturers to install current indirect TPMSs; NHTSA, in analyzing
long-term alternatives, should consider both their impact on the
availability of ABS as well as the potential safety benefits of ABS;
and that NHTSA should provide a better explanation of the technical
foundation for the agency's safety benefits estimates and subject those
estimates to sensitivity analyses.
A. Criteria for Selecting the Long-Term Requirement
1. Tire Safety and Overall Vehicle Safety
OMB stated in its return letter that ``a rule permitting indirect
systems may provide more overall safety than a rule that permits only
direct or hybrid systems.'' OMB said:
Although direct systems are capable of detecting low pressure
under a greater variety of circumstances than indirect systems, the
indirect system captures a substantial portion of the benefit
provided by direct systems. Moreover, allowing indirect systems will
reduce the incremental cost of equipping vehicles with anti-lock
brakes, thereby accelerating the rate of adoption of ABS technology
* * *. Both experimental evidence and recent real-world data have
indicated a modest net safety benefit from anti-lock brakes.
While NHTSA's general obligation under the Vehicle Safety Act is to
improve overall vehicle safety, it is mindful that its specific,
immediate obligation in this rulemaking is to comply with the mandate
of section 13 of the TREAD Act. The agency is seeking to comply with
the mandate and safety goals of the TREAD Act in a way that encourages
innovation and allows a range of technologies to the extent consistent
with providing drivers with sufficient warning of low tire pressure
under a broad variety of the reasonably foreseeable circumstances in
which tires become under-inflated.
2. Statutory Mandate
Section 13 of the TREAD Act mandated the completion of ``a
rulemaking for a regulation to require a warning system in new motor
vehicles to indicate to the operator when a tire is significantly under
inflated'' within one year of the TREAD Act's enactment. As noted
below, the agency tentatively believes, based on the current record,
that a four-tire, 25 percent under-inflation requirement would best
meet the mandate.
B. Relative Ability of Direct and Current Indirect TPMSs To Detect
Under-Inflation
As noted above, current indirect TPMSs work, in part, by adding the
speeds of diagonal sets of tires and subtracting the sum of one set
from the sum of the other. As a result, if all four tires are
significantly under-inflated, and the difference in the tire pressures
is not 30 percent or greater, current indirect TPMSs will not provide a
warning. Similarly, if two tires on the same axle or same side of the
vehicle are significantly under-inflated, current indirect TPMSs will
not provide a warning.
These combinations of significantly under-inflated tires occur
frequently enough that current indirect TPMSs would have provided a
warning in only about 50 percent of the instances in which NHTSA found
significant under-inflation in the February 2001 NCSA survey.
Conversely, current direct TPMSs would have provided warnings in all
those instances.
The following figures indicate how often current direct and
indirect TPMSs would provide warnings when a vehicle has at least one
tire that is at least 30 percent below the placard pressure.
Of the 5,967 passenger cars in the February 2001 NCSA survey, 1,199
(20 percent) had at least one tire that was at least 30 percent below
the placard pressure. Current direct TPMSs would have provided a
warning in every case, while current indirect TPMSs would have provided
a warning in only 653 cases (54 percent).
Of the 3,950 light trucks in the NCSA survey, 789 (20 percent) had
at least one tire that was at least 30 percent below the placard
pressure. Current direct TPMSs would have provided a warning in every
case, while current indirect TPMSs would have provided a warning in
only 359 cases (46 percent).
Thus, of the total 9,917 passenger cars and light trucks in the
NCSA survey, 1,988 (20 percent) had at least one tire that was at least
30 percent below the placard pressure. Current direct TPMSs would have
provided a warning in every case, while current indirect TPMSs would
have provided a warning in only 1,012 cases (51 percent).
Current indirect TPMSs would have failed to provide a warning in
the remainder of the cases for various reasons. Many of the vehicles
had one tire that was 30 percent below the placard pressure, but not 30
percent below the pressure in the other tires. As noted above, current
indirect TPMSs require at least a 30 percent differential in tire
pressure before providing a warning. Other vehicles had more than one
tire that was 30 percent below the placard pressure. As noted above,
current indirect TPMSs cannot detect when all four of a vehicle's
tires, or two tires on the same side of the vehicle or the same axle,
are under-inflated.
The absence of a warning in approximately 50 percent of the
instances of significant under-inflation is a matter of concern given
that many drivers will rely on a TPMS instead of regularly checking
their tire pressure. Data from the July 2001 BTS omnibus survey
indicate that 65 percent of people would be less concerned, to either a
great extent or a very great extent, with routinely maintaining the
pressure of their tires if their vehicle were equipped with a TPMS.\34\
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\34\ NHTSA notes that in its prepared statement submitted in
connection with the February 28, 2002 hearing before the House
Committee on Energy and Commerce on the TREAD Act, OMB stated: The
1-tire standard will provide warnings when 1 tire is underinflated
but will not necessarily detect situations when 2 or more tires are
underinflated. A further weakness of the 1-tire standard is that
consumers may misperceive that their tires are fine (since the
warning light is off) when in fact all four of their tires are
equally underinflated. The 4-tire standard overcomes these problems.
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[[Page 38719]]
C. Analysis of a Fourth Alternative Long-Term Requirement: One-Tire, 30
Percent Under-Inflation Detection
As explained above in section V.A., ``Alternative Long-Term
Requirements Analyzed in Making Preliminary Determination,'' NHTSA
analyzed three alternatives: a four-tire, 20 percent alternative; a
three-tire, 25 percent alternative and a four-tire, 25 percent
alternative.
OMB recommended that the agency analyze a fourth alternative that
would require a vehicle's TPMS to warn the driver when the pressure in
any one of the vehicle's tires is 30 percent or more below the vehicle
manufacturer's recommended cold inflation pressure for the tires, or a
minimum level of pressure specified in the standard, whichever pressure
is higher. (This alternative is referred to below as the ``one-tire, 30
percent alternative.'') The agency's analysis of the benefits and costs
of this alternative follows.
The agency estimates that the one-tire, 30 percent alternative
would prevent 79 fatalities and prevent or reduce in severity 5,176
injuries. The agency estimates that the average per vehicle cost of
this alternative would be $33.34. Since approximately 16 million light
vehicles are produced for sale in the United States each year, the
total annual cost of this alternative would be $533 million. The agency
estimates that the average per vehicle maintenance cost would be
$13.50,\35\ and that the average per vehicle fuel and tread life
savings over the lifetime of the vehicle would be $2.06 and $0.65,
respectively. Thus, the net per vehicle cost of this alternative would
be $44.13, and the total annual net cost would be $706 million. The net
cost per equivalent life saved would be $5.8 million.
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\35\ If the one-tire, 30 percent alternative were the only
alternative available to vehicle manufacturers, the agency
anticipates that the approximately \1/3\ of vehicles not equipped
with ABS would nevertheless comply by means of direct TPMSs. The
approximately $40.91 of maintenance costs for each of those
vehicles, if averaged over the entire fleet, is approximately
$13.50.
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D. Impact of One-Tire, 30 Percent Alternative on Installation Rate of
ABS
OMB said that NHTSA should analyze the impact of adopting its long-
term regulatory alternatives as well as an additional long-term
alternative, a one-tire, 30 percent alternative, on the installation
rate of ABS. Since the additional alternative is the only one that
would permit compliance by means of installing current indirect TPMSs,
and since OMB's suggestion that a TPMS standard could induce increased
installation of ABS is dependent upon the manufacturers' being able to
install that type of TPMS, NHTSA's analysis focuses on that
alternative.
The agency believes there is no reliable basis for concluding that
permitting current indirect TPMSs to comply would lead to a significant
increase in installation of ABS in light vehicles for the following
reasons.
First, the final rule does not mandate the installation of ABS.
Vehicle manufacturers always have the option of providing a measure
that exceeds NHTSA's standards. However, nothing in the final rule
requires manufacturers to install ABS.
Second, the rulemaking record does not contain a reliable basis for
concluding that manufacturers will voluntarily install ABS in
significantly more light vehicles in response to being permitted to
install current indirect TPMSs. When the Alliance addressed the issue
of increased voluntary installation of ABS in its September 6, 2001
comments, it said only that a manufacturer ``may well'' opt to make ABS
standard equipment on models for which optional ABS is currently
available and is currently in high market demand. Further, only one
manufacturer, Toyota, indicated that it might make ABS standard
equipment on more vehicles if indirect TPMSs were allowed. Toyota
provided this indication not in its written comments, but orally in a
meeting with the agency. Nothing requires Toyota to make ABS standard
equipment.
Third, several manufacturers orally indicated that they would not
install ABS on their light trucks even if indirect TPMSs were allowed.
General Motors (GM) and Ford told NHTSA that they would install a
direct TPMS on their trucks, rather than a four-channel ABS and
indirect TPMS, because ABS was significantly more expensive. Further,
the agency notes that in April 2002, GM announced that it would cease
offering ABS as standard equipment on a number of its less expensive
models of cars to make those models more price competitive.
Fourth, it is not economically reasonable for manufacturers to
install ABS voluntarily on significantly more vehicles in response to
being permitted to install current indirect TPMSs. In the absence of
written comments from individual manufacturers indicating that they are
very likely to increase voluntarily their installation of ABS if
allowed to install current indirect TPMSs, NHTSA may not simply assume
that manufacturers will elect to spend $240 per vehicle to install ABS
to save $53, the difference between the cost of a direct TPMS ($66) and
an indirect TPMS ($13). The market for ABS has been static for several
years, with the installation rate at about 63 percent. Absent a market
demand for more installations, a manufacturer would not gain a market
advantage by increasing the percentage of its vehicles with ABS.
In NHTSA's Final Economic Assessment (FEA), the agency states that
although a manufacturer may elect to increase the installation of ABS,
it is solely a marketing decision.\36\ The influence, if any, this
rulemaking might have on their marketing decisions is purely
speculative. There are many factors that influence a manufacturer's
decision to install equipment. Cost impact is only one of them.
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\36\ A copy of the FEA has been placed in the docket.
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E. Overall Safety Effects of ABS
In addition to recommending that the agency assume that the
adoption of the one-tire, 30 percent compliance option would induce
vehicle manufacturers to increase their installation of ABS, OMB also
recommended that the agency take into account the potential safety
benefits of ABS when estimating the benefits of that option. OMB
suggested that ABS could reduce fatalities in light vehicles.
NHTSA has analyzed ABS and has determined that there is currently
no statistically reliable basis for concluding that ABS reduces
fatalities in light vehicles for the following reasons.
First, NHTSA has analyzed the impacts of ABS on light vehicle
fatalities for the past decade, with mixed findings.\37\ In general,
test track results indicate that ABS is a very promising technology
that enables drivers to keep vehicles under control under adverse road
conditions. Under some pavement conditions, ABS allows the driver to
stop a vehicle more rapidly while maintaining steering control, even
during panic braking.
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