DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 571
Docket No. NHTSA-03-15400
RIN 2127-AI54
Federal Motor Vehicle Safety Standards; Tires
AGENCY: National Highway Traffic Safety Administration (NHTSA), Department of Transportation.
ACTION: Final Rule.
SUMMARY: The Transportation Recall Enhancement, Accountability, and Documentation Act of 2000 mandates that we conduct a rulemaking proceeding to revise and update our safety performance requirements for tires. In response, we are establishing new and more stringent tire performance requirements that will apply to all new tires for use on light vehicles, i.e., those vehicles with a gross vehicle weight rating of 10,000 pounds or less, except motorcycles and low speed vehicles. The final rule increases the stringency of the existing high speed and endurance tests, defers action on proposals to replace the existing strength test and the bead unseating resistance test with a road hazard impact test and a different bead unseating test, respectively, adds a low pressure performance test, and defers action on a proposal to add an aging test.
Together with new safety information requirements that we recently established for those tires, the new performance requirements will improve tire safety.
DATES: This final rule is effective June 1, 2007. Voluntary compliance is permitted before that date. If you wish to submit a petition for reconsideration of this rule, your petition must be received by [INSERT DATE 45 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER].
ADDRESSES: Petitions for reconsideration should refer to the docket number and be submitted to: Administrator, Room 5220, National Highway Traffic Safety Administration, 400 Seventh Street, SW, Washington, DC 20590.
FOR FURTHER INFORMATION CONTACT:
For technical and policy issues: Mr. George Soodoo or Mr. Joseph Scott, Office of Crash Avoidance Standards, National Highway Traffic Safety Administration, 400 Seventh Street, SW, Washington, DC 20590. Telephone: (202) 366-2720. Fax: (202) 366-4329.
For legal issues: Nancy Bell, Attorney Advisor, Office of the Chief Counsel, NCC‑20, National Highway Traffic Safety Administration, 400 Seventh Street, SW, Washington, DC 20590. Telephone: (202) 366‑2992. Fax: (202) 366‑3820.
SUPPLEMENTARY INFORMATION:
Table of Contents
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I. Executive Summary
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A. Highlights of the Notice of Proposed Rulemaking
Section 10 of the Transportation Recall Enhancement, Accountability, and Documentation (TREAD) Act mandates that the agency issue a final rule revising and updating its tire performance standards. In response, the agency examined the value of modifying each of the existing tests in its tire standards applicable to tires for light vehicles, i.e., those vehicles with a gross vehicle weight rating of 10,000 pounds or less, except motorcycles and low speed vehicles. In addition, NHTSA examined the value of adopting several new tests. In doing so, it placed particular emphasis on improving the ability of tires to withstand the effects of factors mentioned during the consideration and enactment of the TREAD Act, such as tire heat build up, low inflation, and aging. The agency conducted extensive testing, data gathering and analyses as well as reviewed other existing international, industry and national standards and proposals, and submissions by the public.
As a result of these efforts, the agency identified an array of amendments for revising and updating its tire standards and thereby improving tire performance. In the notice of proposed rulemaking (NPRM) that NHTSA published on March 5, 2002 (67 FR 10050, Docket No. NHTSA-00-8011), the agency proposed to upgrade its existing requirements and test procedures addressing the following aspects of tire performance: tire dimension, high speed, endurance, road hazard impact, and bead unseating. The agency proposed also to add new requirements that would require that underinflated tires and aged tires provide specified levels of performance.[1] The agency recognized the potential significant cost of some of the proposed amendments, but decided that, in view of the broad mandate in the TREAD Act and the uncertainty associated with the analysis of benefits and costs, the most appropriate course of action was for the agency to seek public comment on the wide array of proposals and use the information in the responses to adjust and refine the amendments.
The highlights of the proposal were as follows:
(1) High speed and endurance tests - the current high speed and endurance tests in FMVSS No. 109, New Pneumatic Tires - Passenger Cars, 49 CFR 571.109, would have been replaced with a more stringent combination of testing parameters (ambient temperature, load, inflation pressure, speed, and duration.) The proposed high speed test would have specified test speeds (140, 150 and 160 km/h (87, 93, and 99 mph)) that are substantially higher than those currently specified in FMVSS No. 109 (120, 128, 136 km/h (75, 80, 85 mph)). The proposed endurance test would have specified a test speed 50 percent greater (120 km/h (75 mph)) than that currently specified in FMVSS No. 109 (80km/h (50 mph)), as well as a duration that is 6 hours longer (40 hours total) than that currently specified in FMVSS No. 109 (34 hours total).[2]
(2) Road hazard impact test and bead unseating test - these two tests would have been modeled on SAE Recommended Practice J1981, Road Hazard Impact Test for Wheel and Tire Assemblies (Passenger Car, Light Truck, and Multipurpose Vehicles), and the Toyota air loss test, respectively. These new tests would have replaced the strength and bead unseating resistance tests in the current FMVSS No. 109 with tests that were believed to be more real-world and more stringent.
(3) Low inflation pressure performance - two alternative tests were proposed. Both tests would have utilized tires significantly under-inflated, for instance, 140 kPa (20 psi) for P-metric tires (the low inflation pressure threshold requirement for warning lamp activation in the then proposed Tire Pressure Monitoring System (TPMS) standard, Docket No. NHTSA-00-8572 (66 FR 38982, July 26, 2001)), as the "inflation pressure" testing parameter for standard load P-metric tires.
(4) Aging effects - three alternative tests were proposed that would have evaluated a tire's long term durability through methods different than and/or beyond those required by both the current and the proposed endurance test parameters. The three tests would have used peel strength testing, long-term durability endurance requirements, and oven aging, respectively.
(5) Tire Selection Criteria/De-Rating of P-metric Tires - the agency proposed retaining the de-rating percentage of 1.10 for P-metric tires used on non-passenger car vehicles and revising FMVSS No. 110 to specify that the determination of vehicle normal load ("reserve load") on the tire be based on 85% of the load at vehicle placard pressure.
Also, the agency discussed revising FMVSS No. 110, Tire selection and rims, for passenger cars, 49 CFR 571.110, and FMVSS No. 120, Tire selection and rims for motor vehicles other than passenger cars, 49 CFR 571.120, to reflect the applicability of the proposed new light vehicle tire standard to vehicles up to 10,000 pounds GVWR. It also discussed revising FMVSS No. 117, Retreaded pneumatic tires, 49 CFR 571.117, and FMVSS No. 129, New non-pneumatic tires for passenger cars, 49 CFR 571.129, to replace the performance tests that reference or mirror those in FMVSS No. 109 with those specified in the proposed new light vehicle tire standard.
The agency proposed two alternative implementation schedules for tires: a two-year phase-in under which all applicable tires would have been required to comply with the final rule by September 1, 2004, and a three-year phase-in under which all applicable tires would have been required to comply with the final rule by September 1, 2005. For light vehicles, the agency proposed that all those manufactured on or after September 1, 2004 would have had to comply with the final rule.
The aforementioned proposals are summarized more fully in section IV.B. of this document.
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B. Highlights of the Final Rule
In response to the NPRM, the agency received cost data from commenters and other information that assisted it in refining its assessment of benefits and costs and in choosing amendments to fashion a final rule that will offer the American public enhanced tire safety and be consistent with the principles of Executive Order 12866. The resulting final rule establishes new and more stringent tire performance requirements that apply to all new radial tires for use on passenger cars, multipurpose passenger vehicles, trucks, buses and trailers that have a gross vehicle weight rating (GVWR) of 4,536 kg (10,000 pounds) or less and that are manufactured after 1975, and to all new passenger cars, multipurpose passenger vehicles, trucks, buses and trailers that have a GVWR of 4,536 kg (10,000 pounds) or less. The requirements are fully summarized in section VI.A. of this document.
The agency believes the final rule is a reasoned one that is based on the best currently available information and that will improve tire safety. NHTSA believes that this rule will be effective at ensuring that future tires will have their strength, endurance, and heat resistance evaluated in a way that will increase the required level of performance.[3] As a result, these tires are expected to exhibit less variability in levels of performance and experience fewer blowouts and tire failures. Additionally, the reserve load requirements of FMVSS No. 110, combined with the de-rating of P-metric tires when used on SUVs, vans, trailers, and pick-up trucks, will provide a sufficient safety margin for tires used on light vehicles.
In response to comments from the tire and vehicle industries arguing that the compliance costs were underestimated in the NPRM and in recognition of the limited quantifiable safety benefits, NHTSA has reduced the stringency of some of its proposals and deferred others, to ensure that this rule's safety improvements will be reasonably related to the rule's costs.
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C. Adopted aspects of the NPRM
High speed and endurance -- The agency is upgrading the existing high speed and endurance tests, although to a more modest degree than we proposed. Both the high speed test and the endurance test contain testing parameters (ambient temperature, load, inflation pressure, speed, and duration) that make the tests more stringent than those tests currently found in our tire standards, as well as the tests suggested by industry. Most significantly, the high speed test specifies test speeds of 140, 150, and 160 km/h substantially higher than those specified in the passenger car tire standard. Likewise, the endurance test specifies a test speed 50% higher than that currently specified in the car tire standard. Under the new endurance test, a tire is assessed over 50% more distance than a tire must endure under the current endurance test.
Low inflation pressure performance--The agency is adopting a low inflation pressure test that seeks to ensure a minimum level of performance safety in tires when they are underinflated to 140 kPa (20 psi). That is the minimum level of inflation at which tire pressure monitoring system warnings will be required to be activated. This requirement mirrors conditions of long distance family travel and will assist in ensuring that tires will withstand conditions of severe underinflation during highway travel in fully loaded conditions.
Applicability and LTVs--Given the increasing consumer preference for using light trucks for personal transportation purposes, NHTSA is, for the first time, requiring light trucks to have a specified tire reserve, the same as for passenger cars, under normal loading conditions. The agency is also extending the tire performance requirements for passenger car tires to LT tires (load range C, D, and E) used on light trucks.
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D. Deferred aspects of the NPRM
Road hazard impact--Instead of replacing the current strength test with the proposed road hazard test, the agency is retaining the strength test for passenger car and LT tires. Post-NPRM agency testing data and public comments called into question whether the proposed road hazard impact test, which was modeled after a SAE recommended practice, would provide both a more stringent and more real-world test than the current test. The agency will address these uncertainties in the near future. After it conducts research on tire aging and resistance to bead unseating, it will conduct research on road hazard impact. Based on the test results, it will decide whether to initiate rulemaking to adopt a new or revised test.
Resistance to bead unseating--Instead of replacing the current bead unseating test with a proposal based on a Toyota test, the agency is retaining the bead unseating test and extending it to LT tires. Industry previously recommended dispensing with a bead unseating test because radial tires are easily able to satisfy the current one. Results from the agency's 1997-1998 rollover testing provided a strong rationale for upgrading, rather than deleting, the bead unseating test. Post-NPRM agency testing data and public comments, however, called into question whether the Toyota test provides both a more stringent and more real-world test than the FMVSS No. 109 bead unseating test. The agency will conduct research on bead unseating after conducting its research on tire aging, and, based on the test results, decide whether to initiate rulemaking to adopt a new or revised test.
Aging--At this time, the agency is not adopting a test to address the deterioration of tire performance caused by aging. We proposed three alternatives for an aging effects test that would expose tires to the type of failures experienced by consumers at 40,000 kilometers or beyond. Because we had little data and analysis regarding any of these tests and understood the tire industry to be regularly conducting aging testing, we requested comments on which alternative should be adopted. The tire industry did not, however, disclose any of its testing data or provide any analysis in its comments on the NPRM. However, some industry members have recently begun a dialogue and offered to share data with the agency.
In an attempt to gain a thorough understanding of existing aging test mechanisms and methodologies, as well as data and analysis relating to that testing, the agency is commencing its own research on aging. The agency anticipates publishing a NPRM proposing an aging test in approximately two years after this final rule.
Benefits
At the time of the NPRM, we were able to quantify only very slight safety benefits. Given the reductions in several of our proposals and the deferral of several of other proposals, the benefits of the final rule will be less than we then projected. We now estimate 1 to 4 lives saved and 23 to 102 injuries reduced. Nevertheless, the final rule will increase the required level of performance for all tires and will improve the strength, endurance, and heat resistance of the 5-11% of tires that will have to be redesigned or modified to achieve compliance.
Costs
Although in issuing the proposal we were able to estimate costs for only two of the proposed tests, we estimated that those two tests alone would result in costs of almost $300 million per year. However, given the reductions in or deferrals of some of our proposals, we estimate that the final rule will, in its entirety, result in annual costs for new original equipment and replacement tires of $3.6 million to $31.6 million. The net costs per equivalent life saved will be about $5 million based on the mid-point of cost and discounted benefits estimates.
Effective Dates/Implementation
The agency is providing a 4-year lead time for both tire and vehicle manufacturers. All covered tires and vehicles must comply with the amendments by June 1, 2007. In view of the comments by the tire and vehicle industry regarding the extent and significance of design and production changes that might have to be made as a result of changing requirements in an area that has been not substantively revised in 30 years, NHTSA finds that an effective date of June 1, 2007 is more reasonable than the shorter lead time proposed in the NPRM and is in the public interest.
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II. Background
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A. The Transportation Recall Enhancement Accountability and Documentation Act
Section 10, "Endurance and Resistance Standards for Tires," of the TREAD Act, Pub. L. 106-414, mandates that the agency issue a final rule to revise and update its tire performance standards. However, the Act gives the agency substantial discretion regarding the substance of the final rule. The Act does not specify how the standards should be revised or updated. For example, it does not specify which particular existing performance requirements and test procedures should be improved or how much they should be improved. Likewise, it does not specify which particular new requirements should be added or how stringent they should be.
In response to section 10 of the TREAD Act, the agency comprehensively examined possible ways of revising and updating its tire standards. In doing so, it placed particular emphasis on improving the ability of tires to withstand the effects of factors mentioned during the consideration and enactment of the TREAD Act such as tire heat build up, low inflation, and aging. The agency examined the value of modifying the existing tests in its tire standards. In addition, it examined the value of adopting several new tests.
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B. Safety Problem
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1. Outdated Performance Requirements
Prior to the enactment of the TREAD Act, the Firestone tire recalls in 2000 focused public attention on the agency's passenger car tire standard, FMVSS No. 109. The standard had not been substantively revised since first issued over 30 years ago in 1967. At that time, nearly all (more than 99 percent) of passenger car tires in the U.S. were of bias, or bias belt construction. Accordingly, the requirements and test procedures in FMVSS No. 109 were developed primarily to address bias tires. Today, bias tires have been almost completely replaced by radial tires on passenger cars and other light vehicles. The use of radial tires has grown to the extent that they represent more than 95 percent of passenger tires in both the U.S. and Europe and are used on most other new light vehicles sold in the U.S.
NHTSA does not require that light vehicles be equipped with radial tires, but regulates radial tire performance through FMVSS Nos. 109 and 119. Radial tires are less susceptible than bias ply tires to most types of failures.[4] Also, the switch to radial tire designs resulted in significant improvements in tire performance compared with bias ply tires. Given the superior performance of radial tires, it is easier for them than for bias tires to comply with the requirements of FMVSS No. 109.[5]
While the durability and performance of tires have improved, the conditions under which tires are operated have become more rigorous. Higher speeds, greater loads, extended lifetimes of tires, longer duration of travel[6] and shifting demographics of vehicles sales[7] have all contributed to much greater stresses and strains being placed upon today's radial tires than those endured by earlier generation radial tires.
The characteristics of a radial tire construction in conjunction with present usage and purchasing patterns render the existing required minimum performance levels in the high-speed test, endurance test, strength test[8], and bead-unseating test ineffective in differentiating among today's radial tires with respect to these aspects of performance.
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2. Safety Problems Associated with Tires
Essentially, the size of the tire problem has remained the same over the last eight years. With the increasing sales of light trucks, and the fact that light trucks have more tire problems than passenger cars, the problem has shifted more toward light trucks and away from passenger cars. As discussed in the NPRM, several crash files contain information on "general" tire related problems that precipitate crashes. The more recent of these files are the National Automotive Sampling System - Crashworthiness Data System (NASS-CDS)[9] and the Fatality Analysis Reporting System (FARS).[10]
NASS-CDS data for 1995 through 1998[11] indicate that there are an estimated 23,464 tow-away crashes per year coded by the NASS investigators (relying on the police report of the crash) as having been caused by blowouts or flat tires. Based on that estimate, about one-half of one percent of all crashes are caused by these tire problems. The rate of blowout-caused crashes for light trucks (0.99 percent) is more than three times the rate of those crashes for passenger cars (0.31 percent). Blowouts cause a much higher proportion of rollover crashes (4.81) than non-rollover crashes (0.28), and more than three times the rate in light trucks (6.88 percent) than in passenger cars (1.87 percent).
FARS data for 1999 through 2001 show that 1.10 percent of all light vehicles in fatal crashes were coded by investigators as having had tire problems. Light trucks had slightly higher rates of tire problems (1.34 percent) than passenger cars (0.92 percent). The annual average number of vehicles with tire problems in FARS was 528 (255 passenger cars and 273 light trucks).
A further examination of the FARS data indicates that heat is a factor in tire problems. An examination of two surrogates for heat, the region of the U.S. in which the crash occurred, and the season in which the crash occurred, indicates that the highest rates of tire problems occurred in light trucks in southern states in the summertime, followed by light trucks in northern states in the summertime, and then by passenger cars in southern states in the summertime. The lowest rates occurred in winter and fall. Based on these data, tires on light trucks appear to be more affected by higher ambient temperatures than tires on passenger cars.
Examining tire problems in the NASS-CDS from 1992 to 1999 by types of light trucks and vehicle size indicates that LT tires used on light trucks exhibited more problems than P-metric tires. LT tires are used on vehicle classes identified for this analysis as Van Large B and Pickup Large B groups of vehicles. These groups of vehicles typically consist of the Ύ-ton and 1-ton vans and pick-ups. P-metric tires are used on most of the other light trucks. The data indicate that the average percentage of light trucks in the NASS-CDS having a LT tire problem is 0.84, while the average percent of light trucks having a P-metric tire problem is 0.47 percent. These larger pickups and vans, however, carry heavier loads and may be more frequently overloaded than lighter trucks. In addition, these heavier vehicles are often used at construction sites and may be more apt to encounter nail punctures and experience flat tires. Thus, there may be usage issues that increase the percentage of tire problems for these larger trucks, rather than exclusively a qualitative difference between P-metric and LT tires.
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C. Existing NHTSA Performance Requirements for Tires
The following discussion summarizes existing NHTSA requirements relating to tires.
FMVSS No. 109, New pneumatic tires, 49 CFR 571.109, specifies the requirements for all tires manufactured for use on passenger cars manufactured after 1948. This standard, which was issued in 1967 under the National Traffic and Motor Vehicle Safety Act (Safety Act), specifies dimensions for tires used on passenger cars and requires that the tires meet specified strength, resistance to bead unseating, endurance, and high speed requirements, and be labeled with certain safety information. FMVSS No. 109 applies to passenger car (P-metric) tires produced for use on passenger cars, multipurpose passenger vehicles (MPV), and light trucks (sport utility vehicles (SUV), vans, minivans, and pickup trucks). The standard was adopted from the Society of Automotive Engineers (SAE) recommended practice J918c, Passenger Car Tire Performance Requirements and Test Procedures, which was first issued by the SAE in June 1965.[12] The current FMVSS No. 109 includes four performance requirements for tires:
For the purposes of testing tires to determine their compliance with these requirements, the standard specifies values for several factors, such as tire inflation pressure, the load[13] on the tire, and the rim on which a tire is mounted. The standard specifies permissible inflation pressures (or wheel sizes, in the case of bead unseating test) to facilitate compliance testing. The standard requires that each passenger car tire have a maximum permissible inflation pressure labeled on its sidewall (S4.3). Section 4.2.1(b) lists the permissible maximum pressures: 32, 36, 40, or 60 pounds per square inch (psi) or 240, 280, 290, 300, 330, 340, 350, or 390 kiloPascals (kPa). A manufacturer's selection of a maximum pressure has the effect of determining the pressures at which its tire is tested. For each permissible maximum pressure, Table II of the standard specifies pressures at which the standard's tests must be conducted. The intent of this provision is to limit the number of possible maximum inflation pressures and thereby reduce the likelihood of having tires of the same size on the same vehicle with one maximum load value, but with different maximum permissible inflation pressures.
Closely related to FMVSS No. 109 is FMVSS No. 110, Tire selection and rims, 49 CFR 571.110. FMVSS No. 110 requires that each passenger car be equipped with tires that comply with FMVSS No. 109, that tires on the cars be capable of carrying the maximum loaded vehicle weight, that the rims on the car be appropriate for use with the tires, and that certain information about the car and its tires appear on a placard in the passenger car. FMVSS No. 110 also specifies rim dimension requirements and further specifies that, in the event of a sudden loss of inflation pressure at a speed of 97 km/h (60 mph), rims must retain a deflated tire until the vehicle can be stopped with a controlled braking application. FMVSS No. 110 initially became effective in April 1968.
FMVSS No. 117, Retreaded pneumatic tires, 49 CFR 571.117, establishes performance, labeling, and certification requirements for retreaded pneumatic passenger car tires. Among other things, the standard requires retreaded passenger car tires to comply with the tubeless tire resistance to bead unseating and the tire strength requirements of FMVSS No. 109. FMVSS No. 117 also specifies requirements for casings to be used for retreading, and certification and labeling requirements.
FMVSS No. 119, New pneumatic tires for vehicles other than passenger cars, 49 CFR 571.119, specifies performance and labeling requirements for new pneumatic tires designed for highway use on multipurpose passenger vehicles, trucks, buses, trailers and motorcycles manufactured after 1948, and requires treadwear indicators in tires, and rim matching information concerning those tires. Under this standard, each tire must meet requirements that are qualitatively similar to those in FMVSS No. 109 for passenger car tires. The high speed performance test in this standard only applies to motorcycle tires and to non-speed-restricted tires of 14.5-inch nominal rim diameter or less marked load range A, B, C, or D. In addition, FMVSS No. 119 does not contain a resistance-to-bead unseating test.
A tire under FMVSS No. 119 is generally required to meet the performance requirements when mounted on any rim listed as suitable for its size designation in the publications, current at the time of the tire's manufacture, of the tire and rim associations that are listed in the standard. Further, the tire is required to meet the dimensional requirements when mounted on any such rim of the width listed in the load-inflation tables of this standard. In addition to the permanent marking for any non-matching listed rims, each tire manufacturer is required to attach to the tire, for the information of distributors, dealers and users, a label listing the designations of rims appropriate for use with the tire.
FMVSS No. 120, Tire Selection and rims for motor vehicles other than passenger cars, 49 CFR 571.120, requires that vehicles other than passenger cars equipped with pneumatic tires be equipped with rims that are listed by the tire manufacturer as suitable for use with those tires and that rims be labeled with certain information. It also requires that these vehicles shall be equipped with tires and rims that are adequate to support the vehicle's certified gross weight.
Tire selection under FMVSS No. 120 consists of two elements. With one exception, each vehicle must be equipped with tires that comply with FMVSS No. 119 and the load rating of those tires on each axle of the vehicle must together at least equal the gross axle weight rating (GAWR) for that axle. If the certification label lists more than one GAWR-tire combination for the axle, the sum of the tire's maximum load ratings must meet or exceed the GAWR that corresponds to the tire's size designation. If more than one combination is listed, but the size designation of the actual tires on the vehicle is not among those listed, then the sum of the load ratings must simply meet or exceed the lowest GAWR that does appear.
FMVSS No. 120 also contains a requirement related to the use of passenger car tires on vehicles other than passenger cars. The requirement states that when a tire that is subject to FMVSS No. 109 is installed on a multipurpose passenger vehicle, truck, bus, or trailer, the tire's load rating must be reduced by a factor of 1.10 by dividing by 1.10 before determining whether the tires on an axle are adequate for the GAWR. This 10 percent de-rating of P-metric tires provides a greater load reserve when these tires are installed on vehicles other than passenger cars. The reduction in the load rating is intended to provide a safety margin for the generally harsher treatment, such as heavier loading and possible off-road use, that passenger car tires receive when installed on a MPV, truck, bus or trailer, instead of on a passenger car.
FMVSS No. 129, New non-pneumatic tires for passenger cars, 49 CFR 571.129, includes definitions relevant to non-pneumatic tires and specifies performance requirements, testing procedures, and labeling requirements for these tires. To regulate performance, the standard contains performance requirements and tests related to physical dimensions, lateral strength, strength (in vertical loading), tire endurance, and high-speed performance. The performance requirements and tests in FMVSS No. 129 were based upon those contained in FMVSS No. 109.
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III. Pre-TREAD Act Enactment Agency Response to Safety Problem
Prior to this rulemaking, NHTSA embarked on a program of global harmonization for light vehicle tire standards under the auspices of the United Nations/Economic Commission for Europe's (UN/ECE) World Forum for Harmonization of Vehicle Regulations (WP.29).[14] NHTSA, within the WP.29's Working Party on Brakes and Running Gear (GRRF),[15] had been working cooperatively with other countries to develop a global tire standard that could better assess the safety performance of modern tires.
Beginning in July 1999, the GRRF had been considering a draft global technical regulation (GTR) based on the Global Tire Standard 2000 for New Pneumatic Car Tires (GTS-2000)[16], an industry developed standard. Prior to the enactment of the TREAD Act, tentative consensus within an ad hoc tire harmonization working group of the GRRF concerning the draft GTR had been reached on the following issues: 1) to adopt the ECE R30 high speed test methodology[17] in place of the FMVSS No. 109 high speed test, 2) to keep the current FMVSS No. 109 resistance-to-bead unseating test until NHTSA develops an alternative that is more appropriate for radial tires, and 3) to develop an optional requirement for testing wet grip.
Other issues that had also been under discussion in the ad hoc group prior to the TREAD Act included: a) the U.S.'s suggestion to lower the inflation pressures for and increase the duration of the high speed test (current ECE R30 test), b) the U.S.'s suggestion to agree on the need for tire labeling requirements that are unique to the U.S., such as maximum inflation pressure, and UTQG consumer information, c) the U.S.'s suggestion to identify requirements that should be included as optional requirements, d) assigning to the UN the responsibility for tire plant code registration for a global standard, and e) the U.S.'s suggestion to increase the ambient temperature for the high speed test.
In a February 2001 submission to the docket (Docket No. NHTSA-2000-8011), the Chairman of the GRRF Tire Harmonization Working Group had recommended on behalf of the GRRF that NHTSA adopt a draft text that reflects the current state of deliberations for developing a harmonized tire standard. At its 126th session in March 2002, WP.29 decided that there was little prospect of achieving global agreement at this stage and suspended further work indefinitely. The group, as its final task, submitted comments on the NPRM in this rulemaking. The U.S. representative to the GRRF recused himself from these deliberations.
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IV. Post-TREAD Act Enactment Agency Response to Safety Problem
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A. Tire Testing and Opening of Docket No. 2000-8011
Shortly after the enactment of the TREAD Act, the agency had initiated tire testing at Standards Testing Labs (STL) in November 2000 to evaluate the high-speed performance, endurance performance, and low inflation pressure performance of a limited number of current production tires. The agency had developed a test matrix which focused on the five main parameters currently used in tire testing under FMVSS Nos. 109 and 119: load, inflation pressure, speed, duration, and ambient temperature. Copies of the test matrix and testing results for P-metric tires and for LT tires have been available in the docket (see the Tire Test Matrix in NHTSA Docket No. 2000-8011-1).
In summary, the results of the high speed and endurance tests had indicated that the agency could develop and propose test requirements that were realistic in terms of the test parameters, yet more stringent than the current FMVSS No. 109, FMVSS No. 119 requirements, European Regulation ECE R 30, GTS 2000, and RMA 2000. The proposed test requirements had differentiated tires with better high speed and endurance performance from those with lesser performance. The low pressure validation tests had indicated that tires that were able to successfully complete the endurance testing could also complete an additional 90-minute test at a low inflation pressure, 140 kPa for P-metric tires, thus providing an adequate safeguard for consumers to take corrective action when the low pressure warning lamp proposed under the tire pressure monitoring system rulemaking is activated at a "significantly" under-inflated level.
In September 2000, NHTSA had opened a docket, NHTSA-2000-8011, titled "Tire Testing - Federal Motor Vehicle Safety Standard (FMVSS No. 109)." The purpose of this docket has been to collect tire test data and receive feedback on its high speed and endurance performance testing matrices. At issuance of the NPRM, comments and recommendations from 7 entities had been received in the docket. Additionally, Toyota Motor Company (Toyota) had submitted a copy of its air loss test procedure to the docket. Substantive comments and recommendations in response to NHTSA's testing matrices were discussed in the NPRM.
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B. March 5, 2002 Notice of Proposed Rulemaking (NPRM)
As a result of the aforementioned testing and data collection efforts, the agency identified an array of amendments for revising and updating its tire standards and thereby improving tire performance in a NPRM published on March 5, 2002. Some of these amendments would have upgraded existing tests, while the others would have added new ones.
In the NPRM, the agency proposed to include the new tire performance requirements in Standard No. 139, a new tire standard established in a November 18, 2002 final rule on Tire Safety Information (Docket No. NHTSA-02-13678, 67 FR 69600, November 18, 2002). The standard applies to light vehicle tires. As used in the tire safety information final rule, "light vehicles" are vehicles (except motorcycles) with a gross vehicle weight rating (GVWR) of 10,000 pounds or less.
Under the NPRM, the new standard would have contained requirements and test procedures addressing the following aspects of tire performance: tire dimension, high speed, endurance, road hazard impact, bead unseating, low inflation pressure performance, and aging effects.[18]
The proposed high speed and endurance tests would have replaced the current high speed and endurance tests in FMVSS No. 109, New Pneumatic Tires - Passenger Cars, 49 CFR 571.109, with a more stringent combination of testing parameters (ambient temperature, load, inflation pressure, speed, and duration.) Most significantly, the proposed high speed test would have specified test speeds (140, 150 and 160 km/h (87, 93, and 99 mph)) that are substantially higher than those currently specified in FMVSS No. 109 (120, 128, 136 km/h (75, 80, 85 mph)). Likewise, the proposed endurance test would have specified a test speed 50 percent faster (120 km/h (75 mph)) than that currently specified in FMVSS No. 109 (80km/h (50 mph)), as well as a duration 6 hours longer (40 hours total) than that currently specified in FMVSS No. 109 (34 hours total). At the specified test speed (120 km/h), the proposed endurance test distance (4800 km) would have been almost double the distance accumulated than under the current endurance test (2720 km at 80 km/h). These new testing parameters were based on NHTSA's activities undertaken in response to the TREAD Act, including extensive agency testing, data gathering and analyses as well as agency review of other existing international, industry and National standards and proposals, and submissions by the public.
The proposed road hazard impact test and the bead unseating test were modeled on SAE Recommended Practice J1981, Road Hazard Impact Test for Wheel and Tire Assemblies (Passenger Car, Light Truck, and Multipurpose Vehicles), and the Toyota air loss test, respectively. These new tests would have replaced the strength and bead unseating resistance tests in the current FMVSS No. 109 with tests that were believed to be more real-world and stringent.
In addition to the tests cited above, the proposed standard would have contained tests for two new aspects of performance: low inflation pressure performance and aging effects. By seeking to establish tests for these aspects of performance, the agency was attempting to address concerns raised by members of Congress in hearings preceding the enactment of the TREAD Act that NHTSA's current test requirements do not evaluate how well tires perform either when significantly underinflated or after being in use for several years and being subjected to environmental variables, such as heat. In particular, underinflation and heat were factors highlighted as contributing to failure of the Firestone ATX and Wilderness tires in the TREAD hearings, and in the agency's Firestone investigation (NHTSA Office of Defects Investigation (ODI) investigation number EA00-023).
To test low inflation pressure performance, the agency proposed two alternative tests based on agency testing and data analyses. Both tests would have evaluated tires when they are significantly under-inflated. For instance, 140 kPa (20 psi) for P-metric tires (the low inflation pressure threshold requirement for warning lamp activation in the proposed Tire Pressure Monitoring System (TPMS) standard, Docket No. NHTSA-00-8572 (66 FR 38982, July 26, 2001) would have been used as the "inflation pressure" testing parameter for standard load P-metric tires. To test for resistance to aging effects, the agency proposed three alternative tests that would have evaluated a tire's long term durability through methods different than and/or beyond those required by both the current and the proposed endurance test parameters. The three tests would have used peel strength testing, long-term durability endurance requirements, and oven aging, respectively. The agency solicited comments on which of the two proposed tests for addressing low inflation pressure performance, and which of the three tests proposed for addressing aging effects, should have been chosen for the new standard.
In addition to proposing test procedures for the new standard, the agency also discussed in this document its ongoing and future research plans on tire safety, and sought comments on the future use of shearography analysis (a method of analysis using laser technology) for evaluating the condition of tires subjected to the proposed testing procedures and the plans for revising the Uniform Tire Quality Grading Temperature Grading Requirement testing speeds so that they would have been consistent with the test speeds in the proposed high speed tests.
With regard to tire selection criteria and the de-rating of P-metric tires, the agency proposed retaining the de-rating percentage of 1.10 for P-metric tires used on non-passenger car vehicles and revising FMVSS No. 110 to require that the determination of vehicle normal load ("reserve load") on the tire be based on 85% of the load at vehicle placard pressure.
Finally, the agency discussed revising FMVSS Nos. 110, Tire selection and rims, for passenger cars, 49 CFR 571.110, and 120, Tire selection and rims for motor vehicles other than passenger cars, 49 CFR 571.120, to reflect the applicability of the proposed light vehicle tire standard to vehicles up to 10,000 pounds GVWR, and revising FMVSS Nos. 117, Retreaded pneumatic tires, 49 CFR 571.117, and 129, New non-pneumatic tires for passenger cars, 49 CFR 571.129, to replace the performance tests which reference or mirror those in FMVSS No. 109 with those specified in the proposed new light vehicle tire standard.
Emphasizing that the agency was mindful of the principles for regulatory decisionmaking set forth in Executive Order 12866, Regulatory Planning and Review, and wished to adopt only those amendments that contribute to improved safety, NHTSA carefully examined the benefits and costs of these amendments. The agency noted that its efforts to do so, however, were limited by two factors: 1) the limited time allowed by the schedule specified in the TREAD Act for completing this rulemaking, and 2) the difficulty inherent in crash avoidance rulemakings, stemming from the multiplicity of the factors contributing to the occurrence of any crash and the difficulty of ascertaining the relative contribution of each factor, in linking specific improvements in safety requirements with specific reductions in crashes and resulting deaths and injuries.
The agency, based on the proposed high speed and endurance test, estimated that the benefits of this would have been 27 lives saved and 667 injuries reduced and emphasized that not all benefits could have been quantified, e.g., benefits from the proposed aging test, the proposed low inflation pressure performance tests, the proposed road hazard and bead unseating tests, and aspects of the proposal that address the overloading of vehicles.
The agency estimated that about one-third (32.8 percent) of all tires would have needed improvements to pass the high speed and endurance tests and that the overall annual cost of these tests for new original equipment (64 million tires) and replacement tires (223 million tires) would have been estimated at $282 million for a total of 287 million tires sold annually and the net costs per equivalent life saved would have been about $7.2 million. The agency noted that it anticipated receiving cost data and other information that would enable it to refine its assessment of benefits and costs.
Expressing concern about the overall costs of the rulemaking and the net costs per equivalent life saved, the agency sought comments on the proposed new standard, including its applicability and test procedures, modifications to related existing standards, and lead time provided for manufacturers to achieve compliance.
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C. Post-NPRM Technical Submissions to NHTSA Tire Upgrade Docket
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1. NHTSA Testing At Standards Testing Labs (STL)
The agency conducted tire testing at Standards Testing Labs (STL) to evaluate the performance of tires tested to the high speed and endurance parameters proposed in the NPRM. The agency tested 20 (15 P-metric and 5 LT) current production tires.
For high speed testing, at an ambient temperature of 38° C, all 20 tires tested for a duration of 30 minutes at 140, 150, and 160 km/h with the proposed inflation pressures completed the test without failure. At an ambient temperature of 40° C with the other parameters being the same, all 15 P-metric tires completed the test without failure. For LT tires, 1 of 5 tires tested failed the high-speed test. Testing to these same conditions during Winter 2002 with 40 P-metric and 20 LT tires resulted in failures in 2 P-metric tires and 0 LT tires.
Endurance testing was conducted with the same parameters proposed in the NPRM - load combinations of 90/100/110 percent load, test speeds of 120 km/h, duration of 40 hours, ambient temperature of 40 C, and the inflation pressure of 180 kPa for P-metric tires and 75 percent of maximum inflation pressure for LT tires. Four of 15 tires failed to complete the test, representing a 27 percent failure rate. The same 15 tire brands were tested at the same parameters except the ambient temperature was reduced to 38° C and the loads were reduced to 85/90/100 percent. Under these conditions, 1 of the 15 tires failed to complete the test, representing a failure rate of 7 percent. The one failure was a "Q" speed-rated snow tire that completed the 40-hour duration but failed the post-inspection because of chunking.
For the 5 LT tires tested, 3 of the 5 completed the endurance tests at the proposed parameters, representing a 40 percent failure rate. When the load and ambient temperature were reduced to 85/90/100 percent and 38° C, respectively, all 5 LT tires completed the test without any failures.
The agency also conducted low pressure testing at Smithers Scientific to evaluate Alternative 2 of the proposed low pressure test on the performance of 13 tires (10 P-metric and 3 LT).[19] The proposed 40-hour endurance test was performed on the tires before they were run to the low pressure test. The low pressure test parameters included an inflation pressure of 140 kPa, a speed of 140, 150, 160 km/h, a duration of 90 minutes (30 minutes at each test speed), a 67 percent load. The same tests were performed using 3 LT tires, but at inflation values of 260/340/410 kPa for load ranges C/D/E, respectively. These inflation pressure values represent the lowest inflation pressure provided by tire industry standardizing bodies for a tire load limit.
One of the P-metric tires failed to complete the endurance test and, therefore, was not tested to the low pressure test. The 12 remaining tires tested completed the 90-minute low inflation test without failure.
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2. Rubber Manufacturer's Association (RMA) Design of Experiment (DOE) and Confirmation Testing
Members of the RMA developed a response surface model Design of Experiment (DOE) to assess tire temperatures versus test conditions (inflation pressure, load, and speed), surface type (standard test wheel of 1.7-m diameter versus a flat surface), and ambient temperature. An additional follow-up confirmation round of testing, which contained a broader range of tire types and sizes, was also conducted by RMA.[20]
RMA tested P-metric and LT tires to a matrix of high speed and endurance tests. Seven (4 P-metric and 3 LT) tire sizes of various brands were included in the test protocol. P-metric tires included P235/75R15 for all season, P215/70R15 for standard load "broad line," P265/75R16 for all terrain, and P215/70R15 for snow. For LT tires, the sizes were LT245/75R16 LRE for all-terrain/all-traction, LT 235/85R16 LRE for all season, and 31 x 10.5 R 15 LRC for mud. A total of 145 tires were tested.
The parameters RMA used for its high speed testing for P-metric tires were identical to the agency's, except for the ambient temperature. For LT tires, RMA's test parameters were 10 km/h lower than the agency's proposal for speed (130, 140, 150 km/h), and higher for inflation pressures at 330 and 520 kPa for load ranges C and E tires, respectively. All 42 P-metric tires tested to RMA's proposal completed the 160 km/h step without any failures. Of the 32 LT tires tested, 1 tire failed to complete the 150-km/h step, representing a 3 percent failure rate, and 2 LT tires failed to complete the 160 km/h speed step, a 6 percent failure rate.
For its endurance test parameters for P-metric tires, RMA utilized an ambient temperature at 38° C, a load at 85/90/100 percent of the maximum load rating, the same test speed proposed in the NPRM (120 km/h) and duration at 34 hours. For LT tires, RMA's testing included the same parameters as those for P-metric tires except it utilized a lower test speed of 110 km/h and higher inflation pressures at 285 and 445 kPa for load ranges C and E tires, respectively. For the 30 P-metric tires tested to RMA's endurance test, 2 failed to complete the 100 percent load step (5 percent failure rate). For LT tires, 2 of 32 tires tested failed to complete the 100 percent load step (6 percent failure rate).
The outline of RMA's DOE text matrix, including specific test conditions applied by tire type, as well as a full set of DOE tables, charts, graphs, and data are included as DOE Attachment II to RMA's comments (Docket No. 2000-8011-64).
According to RMA, tires included in the test matrix were selected to cover the appropriate range of technical parameters and to ensure representative high volume in the marketplace. The three "popular" tire sizes chosen by RMA were: 1) P205/65R15, 2) P235/75R15, and 3) LT245/75R16 LRC/LRE. Most of the tires tested by RMA, particularly those used for the confirmation testing, were at the lower end of the speed rating scale, e.g. "Q" through "S" and included snow tires, which represent a small percent of sales of replacement tires in the U.S. A brief summary of RMA's DOE conclusions and recommendations are briefly discussed below. RMA's recommendations and comments on the NPRM proposals are summarized in the following section of this document.
In summary, the RMA concluded from the DOE and confirmation test results that:
1) Speed is the most dominant test parameter. Larger temperature increases are observed when speed is increased compared to changing inflation pressure or load, particularly on a test wheel. According to the DOE, at 80 km/h the average tire temperature is 2° C higher on a 1.7 m test wheel than a flat surface, at 160 km/h the curved surface is 25° C higher.
2) Passenger car and light truck tires require different test conditions on a test wheel, particularly for speed, to achieve comparable levels of severity. The effect of this curved surface of the 1.7 m test wheel is to increase the tire deflection compared to a flat surface. In addition, the combination of the curvature of the tire and reverse curvature of the test wheel results in the footprint of the tire being altered. The footprint shape is altered in a non-representative manner when compared to a flat surface. This altered deflection and footprint area result in substantially higher stresses. This is demonstrated by the higher tire temperatures on a curved versus flat surface.
3) The effect of the test wheel curvature increases substantially with speed. Standing waves, which lead to early tire failure, occur at speeds 10 to 20 km/h lower on a curved surface compared to flat. To have a realistic test that can be related to real-world conditions, it is important to properly adjust test conditions on a curved surface to as closely as possible match those of a flat surface.
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3. Ford Motor Company (Ford) Tire Aging Analysis
In June 2002, Ford presented its analysis on the effectiveness of the aging protocols proposed by NHTSA for FMVSS No. 139. Ford's presentation was comprised of evaluated results obtained from tire investigations and data analysis from experiments based on the parameters discussed in the Notice. Based on the results from these experiments, Ford recommended aging mounted tires with a 50/50 blend of oxygen/nitrogen in an oven for two weeks followed by a peel test to be performed on the tire. They also suggested that it would be more appropriate to test the endurance, high speed, or low pressure performance of a tire aged in this manner.
Ford's observations and conclusions are summarized below:
Results Obtained from Tire Investigations: 1) there is a very strong correlation between cross-link density and peel strength for all of the manufacturing facilities, 2) peel strength decreases exponentially as, over time, cross-link density increases (as cross-link density increases, the elongation at break decreases), 3) since there is a relationship between cross-link density and peel strength, and also a relationship between peel strength and age of the tire, a relationship between cross-link density and age of the tire should also exist, 4) the evidence that cross-link density exponentially increases over time suggests that skim and wedge rubber is aging oxidatively, and 5) the aging mechanism of spare tires is the same as road tires, oxidative.
Results From NHTSA ODI Report on Firestone Wilderness AT Tires: 1) the overwhelming majority of tires analyzed aged oxidatively in the field and oxidative aging is the predominant mechanism in the reduction of peel strength over time.
Adhesion (Peel) Test: 1) although peel testing is an important characteristic of tires, the data for Alternative 1 do not support the use of endurance testing as an appropriate aging condition for the tire because the test procedure does not influence the peel strength to any significant degree, i.e., after 24 hours of testing, only a 10% decline in peel strength is affected, while after 50 hours, a 16.8% decrease is measured, 2) the cross-link density of the skim rubber becomes lower as a result of the conditions at which the endurance test is run and this indicates that anaerobic aging due to severe heat and stress is degrading the rubber properties, 3) field aged tires increase in cross-link density with time, not decrease, 4) the wedge properties of the endurance tested tires also show anaerobic aging and this data shows that significant anaerobic aging occurs during endurance testing of this tire, 5) the field data obtained by both NHTSA and Ford suggest aerobic/oxidative aging.
Michelin's Long-Term Durability Endurance Test: 1) The test is not an appropriate universal aging test because it does not properly age the wedge region of larger tires or tires with a heavier tread mass (in the late 1970s and early 1980s when this test was first developed, tread patterns were more all season than all terrain and the average tire size was smaller), 2) the dynamic aspect of the test is too benign for the nearly 10.5 days of test wheel time required (for passenger car tires, running the tire slightly overloaded (11%) and significantly overinflated (17% - significant because inflation pressure changes have a more pronounced effect than load changes in test wheel tests) at 97 km/h essentially prolongs the test so that oxidative aging can occur but fails to test the belt package in any meaningful way once it is aged), 3) the test is not without merit; the 50/50 oxygen/nitrogen blend does accelerate the oxidative aging mechanism of skim rubber.
Oven Aging: 1) Oven aging tires, either un-mounted or mounted with air, has very little effect on the chemical and physical properties of the belt package rubber; only when mounted with the 50/50 blend do properties significantly change, 2) it is possible, by using the 50/50 oxygen/nitrogen blend, to artificially age tire rubber to the chemical equivalent of 3-4 years in age and, from a chemical aging standpoint, properties of the skim rubber can be aged just as effectively in an oven using the 50/50 oxygen/nitrogen blend as on the test wheel, 3) for oven aging, the wedge rubber ages similar to field-aged tires; contrasting with tires run to the "Michelin" test, which showed severe reversion in the wedge rubber, 4) tires oven aged with the 50/50 oxygen/nitrogen blend are in a condition similar to an older full size spare and, therefore, it may be more appropriate to test the endurance, high speed, or low pressure performance of a tire aged in this manner.
Ford also submitted aging testing results, as well as data regarding the high speed, endurance and low-pressure test. Ford's data have been granted confidential status. Therefore, it is not available for review in the docket. Their recommendations from their high-speed, endurance and low-pressure testing are summarized in the comment summary section of this document.
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4. Goodyear Endurance Testing
In a August 2002 presentation to NHTSA and submission to the docket, Goodyear provided the following comments on NHTSA's proposed endurance test based on additional testing conducted by Goodyear: (1) heat induced damage mode (tread chunking) exhibited in proposed FMVSS No. 139 endurance testing is not representative of real world failures in the field, (2) tires with proven safe field performance will not pass the proposed FMVSS No. 139 due to tread chunking caused by excessive heat build-up due to high speed on curved surface and high load conditions, and (3) tire design changes/compromises to reduce heat induced tread chunking will negatively impact other safety performance characteristics (e.g., wet traction, wet handling, dry traction).
Based on the aforementioned observations, Goodyear concluded that 1) FMVSS No. 139 on a 1.7m curved surface causes shorter footprint length, high footprint pressures and elevated strain energy resulting in higher tire running temperatures, 2) 65 mph with a 10% load reduction on a 1.7m test wheel yields tire temperatures equivalent to FMVSS No. 139 conditions on a flat surface, 3) a tire that did not pass the FMVSS No. 139 test on a 1.7m test wheel due to tread chunking passed when the test was duplicated on a flat surface.
Goodyear stated that it agrees with the agency the test speed needs to be 75 mph on a flat surface but suggests the following revision to the proposal to correlate the speed to an equivalent speed and load on a 1.7m curved surface: 1) reduce the load by 10% to 100% at the final load step to effect a 8° F (4.4° C) reduction in the shoulder surface temperature, and 2) reduce the speed 10 mph, to 65 mph, to effect an 9° F (5° C) reduction in shoulder surface temperature. According to Goodyear, the reduced load and speed parameters would reduce heat induced chunking.
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V. Summary of Public Comments on NPRM
NHTSA received over 5,000 comments on the March 2002 NPRM. The comments were submitted by: vehicle and tire manufacturers and associations, consumer advocacy organizations and individual members of the public. Substantive comments are summarized below.
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A. NHTSA's Proposed Test Procedures
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1. High Speed Test
RMA agreed with NHTSA's proposed conditions for passenger tires but believed that adjustments in speed and inflation pressure are necessary for light truck tires to achieve a similar degree of severity as proposed for passenger tires.
ITRA supported the proposal made by the RMA and stated that NHTSA's proposed high speed tests results generally show heat precipitated tread chunking as opposed to tread separation.
GRRF, JATMA, and ETRTO urged the Agency to adopt the high speed test program as specified in the draft Global Technical Regulation (GTR) submitted to the Agency by the ad-hoc group of WP29/GRRF.
Ford agreed with the agency's position that the current high speed test procedure should be upgraded.
Advocates supported the agency's selection of test speed increments, ambient temperature, inflation pressure, load, and duration with regard to NHTSA's proposed single minimum requirement to be met by all tires.
CU recommended all tires be speed rated and then tested according to the RMA 2000 procedure because the RMA 2000 procedure follows GTS 2000 closely and would provide greater promise for reaching global harmonization than the proposed FMVSS No. 139 test. CU, however, believed that ambient temperature testing conditions, as specified by RMA 2000, should be raised to 40° C to equal typical daytime temperatures in the southern regions of the U.S. during the summer.
RMA, ETRTO, GRRF, and JATMA stated that the temperature increase from 38° C to 40° C will create considerable complexity to the industry since most other tests are run at 38° C and suggest retaining 38° C as the ambient temperature for all tests. PC supported the agency's modification of the temperature parameters in order to better simulate real world conditions.
Ford recommended that the test be conducted at the maximum rated load (105% of the maximum rated load) for the tire and not the 85% condition so that tires would be tested at loads consistent with the critical stress conditions for the tire. GRRF stated that the load percentage used for testing should reflect the vehicle normal load condition but also take into account the effect of the curvature of the test drum. ITRA/TANA commended NHTSA for reducing the load in the parameters of the high speed test from 88% to 85%. CU supported the change in load if the proposed high speed methodology is adopted and stated that it will be beneficial for LT tires to be testing with same load conditions so that that light trucks would also have the same reserve load under normal loading conditions.
GRRF stated that testing on a drum at the lower inflation pressures specified in the NPRM will result in an increase in stress in areas of the tire not usually subject to such high stress levels and may result in some tires having to be "stiffened" by having a greater amount of material in these areas simply to pass the test. RMA stated that the proposal results in more overload (or over-deflection) in light truck tires compared to passenger tires and suggested the following test pressures: LT load range C: 330 kPa; LT load range D: 425 kPa; LT load range E: 520 kPa. Ford suggested testing at various inflation pressures to reflect a wider range of conditions to which tires may be exposed: P-metric 35, 32, 29 psi (241, 220, 200 kPa) Extra Load P-metric 42, 38, 34 psi (290,262, 234 kPa), LT load range C 50, 46, 42 psi (345, 317, 290 kPa), LT load range D 65, 60, 55 psi (448,414, 379 kPa), LT load Range E 80, 73, 66 psi (552,503,455 kPa). Public Citizen supported the proposed inflation pressures for the high-speed test.
GRRF, Ford, RMA, PC, and Advocates believed the test should be replaced with a procedure based on the rated speed capability of the tire. They felt that the road safety interests of the consumer would be better met by using speed values during the high speed test that take into account the speed capability of the tire and the designed maximum speed of the vehicle to which it may be fitted. In lieu of a speed-rating regime, RMA suggested speed steps of 130/140/150 km/h for light truck tires stating the change in predicted running temperature from a flat surface to a 1.7-m test wheel is different for passenger and light truck tires and, therefore, a reduction of 10 km/h in the test speeds for light truck tires to compensate for this effect and maintain a change in severity from flat to test wheel similar to passenger tires is needed.
GRRF stated that a test duration step of 10 minutes has been found to be acceptable in achieving temperature equilibrium and that the intermediate speed step duration is less relevant than the duration at the chosen final speed. CU agreed with NHTSA that the ten-minute speed steps used in RMA 2000 are too short to evaluate high-speed capability.
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2. Endurance Test
ETRTO and GRRF stated that failure mode reached during the test might not reflect real world tire failure mode because of the deflection of the tire on the test wheel.
RMA and ITRA/TANA suggested an alternative test protocol that: 1) reduces load from 110 to 100%; 2) reduces duration from 40 to 34 hours in 4/6/24-hour steps; 3) adjusts light truck tire inflation pressure from 75% of maximum to 81.8% of maximum to reflect a proportional load capacity as shown in the TRA light truck load tables; 3) adjusts light truck tire speed from 120 km/h to 110 km/h to maintain comparable severity from flat to test wheel similar to passenger tires; and, 4) reduces ambient temperature from 40° C to 38° C. RMA stated that for light truck tires, this alternative test proposal adjusts the test conditions to be more equivalent to the tire temperatures that would be produced on a flat surface for the specified test conditions.
GRRF suggested that consideration should be given to combining the proposed endurance and aging tests in order to eliminate unnecessary testing.
CU and Advocates supported the proposed parameters.
GRRF, RMA, and JATMA stated that the test ambient temperature should be 38+/-3° C so the existing equipments can be used without any change. Advocates agreed with the agency that 40° C is a more realistic selection based on the ambient operating temperatures in the southern part of the U.S. and Public Citizen supported the agency's modification of the temperature parameters in order to better simulate real world conditions.
RMA suggested testing at 85/90/100 percent of maximum load for P-metric and light truck tires and argue that the tires in the proposed test are significantly over-deflected (40 to 36%) during the last load/time step of 22 hours. Advocates stated that given the excessive loading of larger light trucks, those usually having GVWR greater than 6,000 pounds, it supports the more demanding alternative discussed by NHTSA. PC stated that NHTSA should adopt load specifications of 100, 110 and 115 percent to adequately provide for the loading conditions of these heavier commercial vehicles over 6,000 GVWR.
RMA suggested an adjustment in inflation pressure for LT tires from 75% to 81.8%, following the respective load/pressure formulas for passenger and light truck tires as defined by the TRA. According to RMA, this reflects a load capacity difference between passenger and light truck tires at the same percent pressure. ITRA/TANA stated that LT tires with heavier casing construction should be tested at pressures not less than 80 percent of their maximum inflation pressure because their designs generate a much higher temperature than P-metric tires when conducted on a curved test wheel in a lab instead of a flat road surface. Advocates supported the inflation parameters.
RMA believed that the increase in speed is the most significant change to the endurance test and states that the speed increase from 80 to 120 km/h produces an average increase of 30° C in tire temperatures for P-metric tires over FMVSS No. 109 and an average increase of 40° C for LT tires. RMA suggested a reduction of 10 km/h for the LT tire test speed in order to maintain the same relative severity from flat to test wheel as that which occurs with passenger tires. Ford stated that increasing the test speed from 50 mph (80 km/h) to 75 mph (120 km/h) causes reversion in the tire and is not representative of real world tire performance.
Ford suggested that the agency adopt the current endurance test protocols as defined in FMVSS No. 109 for a period of 48 hours at the end of the current protocol and that FMVSS No. 119 be modified to include an additional test step at 130% rated load. Ford stated that their data indicate that tires with marginal sidewall designs will have difficulty passing this added test step. Advocates and PC supported the 40 hours duration as being a sufficiently stringent test.
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3. Low Inflation Pressure Performance
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a. Generally
GRRF, ETRTO, the Alliance, and JATMA asserted that the proposed endurance and high-speed tests obviate the need for a low inflation pressure test.
GRRF, JATMA, ETRTO, and ITRA/TANA opposed to the establishment of 140 kPa as an acceptable level of inflation pressure at which to carry out a low inflation pressure test. GRRF stated that the use of inflation pressures as low as 140 kPa (20 psi) for the proposed low pressure test, taking into account the drum and the duration of the test, will result in testing at abuse levels well outside any that could be reasonably expected to be taken into account in tire design and are outside operating recommendations given by the tire industry.
RMA stated that the low-pressure test should be run at 90% of the tire's maximum load capacity rather than 100% so that 20 psi is not 42% below the required test load but at 30%, the maximum allowed under the TPMS final rule.
The Alliance and Ford stated the low-pressure testing protocols, proposed in the notice, are not representative of real world aging conditions because the 40-hour endurance test preceding the low-pressure tests causes the belt region to age anaerobically. Results from these tests showed a tremendous heat build up in the tire which leads to tread chunking, a benign failure mode rarely if ever seen outside of a racetrack. They stated that it would be better to run a low-pressure test on a tire that had gone through an aging procedure that correlates to actual field aging of tires.
CU stated that the NPRM does not provide enough information to determine when exactly the tire would be run to the low-pressure conditions following successful completion of the endurance test. They recommended that the tire be allowed to cool down for a minimum of three hours at the ambient test condition before starting the low-pressure test.
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b. Low Inflation Endurance
RMA, ITRA and TANA favored Option 1 stating that the Option 2 conditions are so severe that the tires experience thermal runaway (i.e., the temperature did not stabilize within 30 minutes) during the required steps. RMA recommended a modified Option 1 test with adjusted test conditions which they state more accurately reflect performance on the flat surface and to more closely reflect the conditions that should exist when the TPMS warning is given: 1) lowers LT tire speed from 120 to 110 km/h to maintain consistency with the RMA proposed endurance test conditions; 2) reduces the test load from 100 to 90% of the tire's maximum load capacity to reasonably simulate the effect of a 30% decrease in inflation pressure when the test pressure is specified at the minimum pressure listed in the NPRM at paragraph S6.4.1.1.1; and, 3) extends the time from 15 minutes to one hour for post-test measurement of inflation pressure.
CU favored an endurance type TPMS low pressure test over the high speed version proposed because they believe it is more representative of conditions consumers are likely to encounter. However, CU believed that testing the tires for 90 minutes at 75 mph represents too short a distance (just 112.5 miles) and is well below the typical fuel range of most vehicles. CU recommends that the test duration be at least four hours at 75 mph, simulating a distance of 300 miles and is more representative of the fuel range of a typical vehicle.
Advocates regarded this alternative as undemanding and insufficient for determining the underinflation tolerance of current light vehicle tires. Public Citizen believed that the stringency of the test is highly questionable considering that all of the tires tested passed the test.
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c. Low Inflation High Speed
GRRF noted surprise that a test load of only 67% is quoted because it seems impractical for a consumer to reduce the vehicle load following a TPMS warning indication.
JATMA stated that this test is unjustified to demand tire performance of this type because consumers would not continue driving at above 140 km/h for over one hour with a tire pressure warning.
Ford supported the low-pressure high-speed test if the tires are aged in an oven with a 50/50 blend of oxygen and nitrogen and an allowance is made for a 2-hour break-in period at 180 kPa and 120 km/h at 85% load, similar to the FMVSS No. 109 high-speed test. Ford stated that the aging process and test protocol more closely approximates a full size spare that is put into service after 3-4 years: oxidatively aged and potentially under-inflated. The break-in period would give the aged tire an opportunity to be worked before being deflated and run to the low pressure test procedure and does not cause reversion in wedge rubber of the tire.
Advocates and PC supported the parameters of this test. However, Advocates regarded a 67 percent load as completely unrealistic and recommends that the agency consider raising the loading percentage for the low pressure/high speed test from 67 percent to 100 percent or 110 percent.
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4. Road Hazard Impact
RMA stated the current FMVSS No. 109 plunger test should remain only for bias ply tires because radial tires are not susceptible to the type of failure that the current plunger tests was designed to prevent.
RMA, GM, the Alliance, ETRTO, and GRRF stated that the SAE J1981 test was developed as a wheel damage test, to test a wheels ability to withstand potholes and other anomalies, and has very limited use or experience within the industry as a tire test and significant work will be required to develop it into a tire test. RMA, ITRA/TANA, JATMA, GM, Alliance, and Advocates stated that a road hazard test, if NHTSA feels it is necessary, should be deferred for further study and research and to not be included in the proposed FMVSS No. 139.
Ford, the Alliance, and CU recommended that the agency retain the current test and Ford and CU suggest that the agency augment the stringency of the test. Ford stated that it currently uses twice the value specified in FMVSS No. 109 as a corporate specification for their tire suppliers and this level provides a reasonable indication that radial tires will exhibit good resistance to rock inducted tread damage.
Advocates, PC, and CU stated that NHTSA needs to explore other methods using more sophisticated means of evaluation, e.g., shearography, for damage. GM noted that any anomaly from the pendulum impacts in its testing was undetectable by visual inspection.
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5. Bead Unseating
RMA and GRRF believed that a bead-unseating test is unnecessary for radial tires. RMA, and ITRA/TANA suggested that if a bead unseating test must be maintained, then the current test be retained rather than adopting a completely new test. However, they believed that it does need to be modified to take into account the aspect ratio of tires. ITRA and TANA asked that retread tires be exempt from the proposed tests because the bead of the tire is part of the original casing and is not altered in the retreading process, and, as such, there would be redundancy in testing the original casings.
GRRF, Toyota, the Alliance, CU, and Ford stated that the introduction of this revised test without further validation would seem to be premature at this stage. They asserted concerns regarding the lack of a fully defined procedure, the specification of the test equipment, the costs of equipment, and the availability of suitable equipment on the open market. Several commenters, including Toyota, Ford, and the Alliance, asserted that there are significant differences between the agency's proposal and Toyota's test and/or certain specifications that need refinement, such as the load values, specifications for the test wheel/rim, inflation pressures, test device methods, and lateral force.
PC and Advocates supported the agency's proposal for the air loss bench test method because the test is independent of vehicle type but do not support the 200 millimeters per second as being satisfactory because they say it reveals nothing about how a tire would perform in a skid when the vehicle encounters either a pothole or a raised fixed object on the roadside applying an extremely rapid lateral, peak load to the tire. Advocates, however, questioned whether the test advances tire safety if all current production tires would pass the test.
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6. Aging Effects
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a. Generally
RMA and ITRA/TANA stated that none of the options in the NPRM are accepted industry tests with a proven relationship to actual tire performance. RMA and GRRF added that any aging test would be redundant in light of the revised high-speed and endurance tests plus a new low-pressure test.
The Alliance and ETRTO stated that the three test options proposed artificially decay of the materials in the tire structure, but those decays do not reflect what occurs in "real life" over a long period of service.
Ford stated that the predominant factor for tire aging in normal service is aerobic/oxidative aging, which may be accelerated by heat and cites to the NHTSA Office of Defects Investigation (ODI) Engineering Analysis Report on Firestone tires in support of this statement. Ford and the Alliance stated that the proposed tests do not appear to age the tire aerobically/oxidatively. Ford recommended aging mounted tires with a 50/50 blend of oxygen/nitrogen in an oven 70° C for 2 weeks. After this oven aging, they recommend a peel test be performed on the tire and suggest that it may be more appropriate to test the endurance, high speed, or low-pressure performance of a tire aged in this manner.
ITRA/TANA argued that retreads should be exempt from this test.
PC and Advocates asserted that shearographic analysis is critical in accurately determining aging test compliance.
Consumers Union believed further investigation of a more suitable procedure is needed.
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b. Adhesion (Peel) Test
RMA stated that the proposed adhesion peel force test is the least appropriate option due to the following reasons: 1) ASTM-D413 is a peel adhesion test used in the industry to monitor trends and detect large shifts in historic levels and, under the best scenario for minimizing variability, has a 16.8% inherent variability, 2) the test is evaluating only a component of the tire, not the tire's overall performance, 3) peel force does not correlate with field performance, or, at a minimum, a recognized industry test wheel test - the peel adhesion test is not a separation-initiating test, it relates only to propagation 4) there is a lack of mechanical and chemical interaction as would occur in actual field.
GRRF and JATMA opposed this test stating that the proposals do not specify which of the several interfaces of the belt construction are to be tested.
ETRTO stated that the ASTM method is known by the industry to evaluate the vulcanized cord ply, not cut specimens from the tire.
CU believed that the peel test is not sufficiently repeatable or precise and urged NHTSA to conduct more research to develop a practical and efficient method of testing the effects of tire aging.
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c. Michelin's Long Term Durability
RMA, JATMA, GRRF, and CU did not support this test because of its length and inherent cost.
ETRTO and JATMA stated that the use of pure oxygen for inflating tires, presents a danger of explosion and requires special safety procedures to be implemented in the laboratories.
JATMA stated that the test ambient temperature should be 38+/-3° C so existing equipments can be used without any change. JATMA also states that the NHTSA test criterion that no reduction of inflation pressure from initial test pressure is not possible because O2 is consumed during the test.
PC supported this test as a starting point for the proposed aging test.
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d. Oven Aging
ETRTO asserted that this test will cause an extended vulcanization of all rubber components inside a tire and does not represent real world' service conditions where the area subjected to heating and to repeated stresses is that inside the edges of the tread area.
RMA, ITRA/TANA, and GRRF believed this test is a more valid measure of tire performance than Option 1 and significantly less onerous than Option 2. RMA recommended the following modifications if the agency chooses to pursue this test: 1) lower the aging temperature from 75 to 70° C. 70° C is an industry standard for aging of rubber compounds and used by some companies for aging of tires prior to test, and 2) adopt the ambient temperature, inflation pressures, and speed from the RMA recommended endurance tests with steps of: a) 4 hours at 85% load, b) 6 hours at 90% load, c) 14 hours at 100% load.
JATMA stated that a 15-day test is not suitable for mass production management. JATMA further states that the test ambient temperature should be 38+/-3° C so the existing equipments can be used without any change.
CU stated that this procedure does not resemble what consumers experience in the real world with tire aging. In real world conditions, tires do not heat up evenly, and it is often the hot spots and dynamic flexing that define the weak link in tire design.
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B. Application of New Standard/Deletion of FMVSS No. 109
RMA and TRA recommended that the proposed FMVSS No. 139 apply to new pneumatic radial tires on powered motor vehicles (other than motorcycles) that have a gross vehicle weight rating (GVWR) of 10,000 pounds or less and that were manufactured after 1975 and that tires designed for severe snow conditions, speed restricted tires, various trailer tires for special use, temporary service spare tires, and all bias tires should be excluded from FMVSS No. 139 and continue to be certified under existing FMVSS Nos. 109 and 119. RMA suggests that, under FMVSS No. 139, a passenger tire should be defined as one intended for normal highway service and its size designation typically shown as "P" metric or "Hard" metric and a light truck tire should be defined as one intended for normal highway service and its size designation includes "LT" and is load range "C", "D", or "E". JATMA requests that performance requirements for deep tread depth snow tires be stipulated apart from FMVSS No. 139 because of their special usage and design characteristics, e.g., deep grooved tread.
JATMA and GRRF stated that the tire size designation, in addition to the load range, should be clearly stipulated for LT tires. GRRF stated that depending on tire size, some high load capacity LT tires correspond to a gross vehicle mass greater than 10,000 lbs.
SEMA, ITRA/TANA, Denman and Specialty Tires requested that limited-production specialty radial and bias-ply tires remain subject to the current testing procedures of FMVSS Nos. 109 and 119 because (1) tires manufactured in limited production do not present a general safety issue; (2) limited production specialty bias-ply tires cannot meet the standard of proposed FMVSS No. 139 and will be unfairly outlawed; (3) the potential cost for small businesses to otherwise comply with these rules would not be justified; and (4) NHTSA testing procedures and requirements result from the testing and analysis of solely radial tires.
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C. Modification of Application of FMVSS Nos. 110 and 120
AIAM believed that NHTSA inadvertently proposed a prohibition on the use of Load Range E tires on vehicles exceeding 10,000 lbs. GVWR by, in S5.1 .I of FMVSS 120, requiring each vehicle to be equipped with tires complying with FMVSS No. 119. AIAM recommends that NHTSA revise S5.1.1 of FMVSS 120 to permit the installation of tires meeting the requirements set forth in FMVSS No. 139 and the rims listed in accordance with FMVSS No. 139 on vehicles exceeding 10,000 lbs. GVWR, as long as the tire load rating is not exceeded.
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D. Modification to FMVSS Nos. 117 and 129
ITRA/TANA recommended that retreaded tires not be subjected to the proposed road hazard and bead unseating tests because the retread process does not affect the structure of an original casing and it is redundant to test a casing twice.
GRRF stated that principle of requiring retread tires to meet the same performance requirements as new tires is followed in the United Nations ECE Regulations 108 and 109 for car and truck retread tires, respectively.
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E. De-rating of P-metric Tires/Tire Selection/Load Reserve
RMA and GRRF supported NHTSA's retention of the 1.10 load service factor used to reduce the load rating of passenger car tires when installed on an MPV, truck, bus, or trailer, as specified in Part 571.110 Paragraph S4.2.2.2 of the proposed rule. RMA believed that this reduction in load rating is necessary for the reasons stated by NHTSA and is also appropriate to reduce the load rating for passenger car tires used on light trucks, vans, SUVs, and trailers for the following reasons: 1) higher stress on the tire due to the higher center of gravity of these vehicles; 2) more severe service conditions as compared to passenger cars; 3) greater potential for overload due to open cargo areas and increased likelihood for towing; and 4) more tire related problems on light trucks, SUVs, and vans.
RMA and GRRF stated that selection based on vehicle normal load not exceeding 88% of the tire maximum load would reduce the potential for overloading of tires.
GM recommended that the tire selection criteria not be linked to the load used in the high-speed test.[21]
The Alliance, AIAM, Subaru, Honda, and GM strongly recommended that the tire selection criteria in the proposed standard be modified as follows: 1) de-rating of the tire load capacity by dividing by 1.10 be applied only when comparing the GAWR with the vehicle maximum load and not on the vehicle normal load on tire for passenger car tires used on MPVs and light trucks; and 2) for vehicle normal load on a tire, even when passenger car tires are used on MPVs and light trucks, use 88% of the maximum load rating of the tire as marked on the sidewall. These vehicle manufacturers asserted that a lack of attention to the influence on vehicle design could lead to potentially serious unintended consequences (e.g., increasing tire size beyond the need to provide adequate load capacity could raise the center of gravity of the vehicle, which may adversely affect it handling and stability and increase the likelihood of rollovers in some situations).
Ford agreed with the agency that tire robustness could be increased through additional load margin in the application or rating of tires. Ford recommended that the agency require tires to be tested at 105% of their rated load for all vehicle applications 10,000 lbs. GVWR and below. They believed that this additional 5% reserve capability at the maximum rated load condition would provide increased robustness for tire application on all vehicles, not only in OE applications.
PC and Advocates commended the agency for requiring LT tires to provide for a reserve load. However, they believe that a 15 percent load specification does not adequately account for the typical loading conditions for the range of these vehicles. PC recommends that the agency require between an 18 and 20 percent reserve load for vehicles that exceed the 6000 lbs. GVWR. Advocates urged the agency to consider a reserve figure of 18 percent for all light trucks or, in the alternative, a reserve figure of 18 percent for those from 6,001 pounds to 10,000 pounds GVWR.
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F. Lead Time
RMA, ETRTO, JATMA, and GRRF stated that it would not be possible to comply with effective dates of September 1, 2003 for passenger car tires, and September 1, 2004 for light truck tires. RMA added that if their recommended changes are accepted, the number of modifications will not be as great and compliance could be accomplished on a more expedited basis, possibly within five (5) years from the date of the final rule.
JATMA stated that a 5-year lead time is required in case of tires supplied to original equipment manufacturers to evaluate and achieve the target performance for driving stability, riding comfort, and noise etc. Also, they stated that facilities need to be increased, test procedure needs to be formed, and employees need to be trained.
The Alliance, GM, Ford, DC, and Mitsubishi recommended that the new tire performance requirements and the amended vehicle requirements of FMVSS NO. 110 become optional as soon as the final rule is published, and become mandatory on September 1, 2007. They requested the longer lead time because of the number of tires that will have to be changed in terms of materials/compounds or construction, and the time required to make these changes will have indirect effects on the vehicles which will require revalidation for braking, dynamics, fuel consumption, ride, handling, and noise/vibration, including legal noise requirements. Additionally, the Alliance stated that a tire designed to the new requirements cannot be mass-produced until it has been matched to a given vehicle, and the vehicle has been validated for braking, vehicle dynamics, fuel economy, ride, handling, etc. Therefore, the tire and vehicle effective dates must be the same.
DC stated that it cannot begin to conduct necessary vehicle development and tuning programs until an adequate supply of tires meeting any new regulations become readily available from the tire manufacturers (in quantities, styles, and sizes sufficient for vehicle development). They strongly urged that there must be at least a two year lag time between the sufficient availability of development tires meeting any new requirements and the vehicle level phase-in or effective date scheduled.
Advocates urged NHTSA to consider a one-year compliance delay from the date of a final rule effective on September 1, 2002, and believes that LT tires need to be improved just as quickly, if not more quickly, than P-metric tires and a delay in compliance for LT tires is not in the best interest of vehicle and traffic safety.
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G. Shearography Analysis
JATMA stated that shearography is suitable for evaluation of new compound and new tire structure of developing products, but is too expensive and not suitable for a test to assure the quality of mass production goods.
The Alliance, Ford, ETRTO, GRRF, and ITRA/TANA stated that all shearography analysis techniques rely on a subjective assessment by a skilled operator and the present state of technology is such that they may not be acceptable as a regulatory control requirement.
PC supported the use of shearography analysis in conjunction with visual inspection. Additionally, Public Citizen recommended that the agency devise a list of all the possible indications of tire failure.
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H. Revise UTQG
ETRTO, GRRF, and CU suggested that test requirements for Temperature in UTQG are useless once the correct service description including the Speed Symbol is required for the tires, which are then tested according to the corresponding high-speed test schedules in UN/ECE Regulations 30 and 54.
RMA urged NHTSA not to revise the existing UTQGS scope and testing conditions at this time.
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I. Additional Questions
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1. Opportunity to Harmonize
The Alliance, ETRTO, RMA, the Center for Regulatory Effectiveness (CRE), and GRRF stated that the adoption of a UN/ECE Regulation 30 type test, such as the GTS-2000 or proposed GTR, would help to ensure that safety standards are consistent worldwide and that the burden on industry through having to meet several differing standards of various countries is removed. CRE also suggested that NHTSA is obligated to consider the following voluntary consensus standards - ISO 10191, SAE J1561, and SAE J1633/ISO 10454 under the National Technology Transfer and Advancement Act. RMA argued that this action would assist the breaking down of barriers to trade and improve the acceptability of USA-produced tires in a global market.
RMA asserted that NHTSA's proposal might constitute a technical barrier to trade in violation of the WTO Agreement on Technical Barriers to Trade
The Alliance stated that, even if the agency considers the current harmonization proposal unacceptable, the agency should commit to developing a harmonized proposal.
Advocates stated that NHTSA could use the data and testing protocols of the optional test for wet grip of tires discussed in the actions of the World Forum for Harmonization of Vehicle Regulations (WP.29) Working Party On Brakes and Running Gear (GRRF) as a departure point for determining how best to establish tire adhesion requirements to be included in the proposed new Standard No. 139.
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2. "Real-world" Testing Procedures
ETRTO stated that "real-world" testing procedure need to be pursued by defining accelerated test conditions that reflect the effective failure mode of the tires in service.
GRRF supported the approach of using controllable, laboratory based tests wherever possible and provided that they reproduce in-service conditions.
Ford stated that vehicular testing is not practicable due to variation in vehicle size and loading and the wide range of wheel/tire combinations and that the tire standard should continue to be an equipment standard and that tires should continue to be certified by tire manufacturers.
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3. Vehicle Model Year 1975
GRRF supported the cut-off date of 1975 and suggests that consideration is given to the retention of FMVSS No. 109 for tires for earlier vehicles.
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4. Required Inflation Pressures
GRRF and ETRTO suggested that all U.S. tires should be marked with inflation pressures expressed in kPa, as per the internationally recognized standard units.
RMA stated that inflations pressures of 32, 36, 40 and 60 psi should be retained in the existing FMVSS No. 109 standard, but should not be included in the new FMVSS No. 139.
The Alliance and Ford believed the four pressures should be retained for tire rating and testing.
The Alliance requested that NHTSA remove the current and proposed requirement to round the psi equivalent of kPa to the next highest whole number, and to round the pound equivalent of kilogram to the closest whole number.
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J. Other
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1. Test Condition Tolerances
RMA suggested that NHTSA adopt the tolerances listed in ASTM-F-551 Standard Practice for Using a 67.23-in. (1.707-m) Diameter Laboratory Test Wheel in Tire Testing.
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2. Tire Pressure Load Reserve Limit
RMA suggested that NHTSA should adopt a specific tire pressure reserve limit and comments that they will be petitioning the agency for such a ruling in the near future.
RMA and ETRTO stated that the agency's estimate that the proposed standards will impose costs of $282 million on the tire industry is grossly inaccurate. RMA estimated that the first year costs would exceed $1.5 billion with a continuing annual cost to comply in excess of $400 million depending on the options chosen for the final rule.
ITRA stated that the agency's estimates also do not include small manufacturers and foreign manufacturers that import tires to the U.S, and retreaders, and that the proposed regulation could result in the downfall of the retread industry.
RMA, SEMA, ITRA/TANA, Denman, Hoosier, and Specialty tires stated that no cost/benefit analysis has been undertaken for limited production bias-ply and radial specialty aftermarket tires and the new testing requirements associated with NHTSA's proposed FMVSS No. 139 will jeopardize the specialty aftermarket tire industry unless special dispensation is made for these manufacturers. SEMA stated that at least three separate specialty tire manufacturers, Denman, Specialty Tires, and Hoosier are small businesses employing less than 1,000 people.
GM and the Alliance stated that NHTSA has not considered the potential influence of changes to the tire on the performance of the vehicle and that vehicle modifications of significant magnitude would cost the industry substantial amounts in investment and unit costs per vehicle.
GRRF asserted that the analysis of benefits appears to be incorrectly based on the assumption that the problems recently experienced have been caused primarily by incorrect design rather than by difficulties in manufacture, improper application, general poor maintenance or abuse during service.
The Alliance stated that the basis for the estimated benefits is unsubstantiated because of the lack of specific information on the causes of tire failures and because of the agency's inability to estimate what proportion of tires would need improvement and by what amount.
Advocates argued that there is little doubt that a reduction in tire failure rates would result in fewer blowouts and, therefore, fewer rollover crashes. They also asserted that tire failures and their role in crashes are severely underreported and, therefore, that the benefits are much greater than the agency is able to quantify. Advocates agreed with the agency that the benefits of stronger standards ensuring greater speed and heat tolerance for both P-metric and LT tires are intuitively apparent even though it is typically more difficult to quantify benefits for crash avoidance rulemaking proposals than for crashworthiness proposals.
PC argued that the resulting societal costs (e.g., loss of workplace productivity, fatalities, medical costs, property damage costs and costs of travel delay on congested roadways) of motor vehicle crashes must be considered when estimating the benefits of a proposed regulation and that reducing the variability of tires could yield benefits from the proposed tests.
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VI. Agency Decision regarding Final Rule
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A. Summary of Final Rule and Rationale
The agency is establishing a single standard for light vehicle tires, FMVSS No. 139, New Pneumatic Radial Tires for Light Vehicles. Under this standard, light vehicle tires are required to meet a high-speed test, an endurance test, a low inflation pressure performance test, a resistance-to-bead unseating test, and a road hazard impact/strength test. The standard applies to tires for passenger cars, multipurpose passenger vehicles, trucks, buses and trailers with a gross vehicle weight rating (GVWR) of 4,536 kilograms (10,000 pounds) or less, manufactured after 1975.[24] The following chart compares the types of test requirements that currently exist, those that have been suggested by third parties, and those are being established by this agency:
| TESTS | FMVSS 109 |
FMVSS 119 |
GRRF Draft GTR |
GTS-2000 | RMA 2000 |
ECE R30 |
FMVSS No. 139 (As adopted) |
|---|---|---|---|---|---|---|---|
| High Speed | X | - | X | X | X | X | X |
| Endurance | X | X | X* | X** | X | - | X |
| Low pressure performance |
- | - | - | - | - | - | X |
| Strength; or Road Hazard Impact |
X - |
X - |
- | - | - | - | X |
| Bead Unseating |
X | - | X*** | - | - | - | X |
| Accelerated Aging |
- | - | - | - | - | - | - |
Both the high speed test and the endurance test specify testing parameters (ambient temperature, load, inflation pressure, speed, and duration) that make the tests more stringent than those tests currently found in FMVSS Nos. 109 and 119, as well as the tests suggested by industry. Most significantly, the proposed high speed test specifies test speeds (140, 150 and 160 km/h (87, 93, and 99 mph)) substantially higher than those specified in FMVSS No. 109 (120, 128, 136 km/h (75, 80, 85 mph)). Likewise, the endurance test specifies a test speed 50% higher (120 km/h (75 mph)) than that currently specified in FMVSS No. 109 (80km/h (50 mph)), as well as a duration 2 hours longer (24 hours) in the final load step than that proposed in the NPRM (22 hours). At the specified test speed (120 km/h), the endurance test mileage (2,550 miles) is 50% longer than the mileage that a tire endures under the current endurance test (1,700 miles).
The final rule also adopts a low inflation pressure performance test that seeks to ensure a minimum level of performance safety in tires when they are underinflated to 140 kPa (20 psi).
Instead of replacing the current strength test in FMVSS No. 109, the agency is retaining that test for passenger cars and retaining the strength test in FMVSS No. 119 for LT tires. Agency testing data and public comments called into question whether the test proposed in the NPRM, a road hazard impact test that is modeled after a SAE recommended practice, is both more stringent than the FMVSS No. 109 "plunger test" and correlates well with actual field performance. The FMVSS Nos. 109 and 119 strength tests will remain until the agency completes its research on road hazard impact and decides whether to initiate rulemaking to adopt a new or revised test.
The final rule also retains the current FMVSS No. 109 bead unseating test and extends it to LT tires. Industry has previously recommended to the agency that the current bead unseating test be deleted from the standard because radial tires are easily able to satisfy the test. Results from the agency's 1997-1998 and 2001 rollover testing, however, provided a strong rationale for upgrading, rather than deleting, the bead unseating requirement in FMVSS No. 109. The agency proposed a new bead unseating test that is based on a test currently used by Toyota, which uses test forces more stringent than those in current FMVSS No. 109 and appeared more applicable to radial tires. Agency testing data and comments, however, called into question whether the Toyota test provides both a more stringent and more real world test than the FMVSS No. 109 bead unseating test. The FMVSS No. 109 bead unseating test will remain in the standard until the agency completes its research on bead unseating and decides whether to initiate rulemaking to adopt a new or revised test.
At this time, the agency is not adopting a test to address the deterioration of tire performance caused by aging. The proposal set forth three alternatives for an aging effects test: the adhesion (peel) test, Michelin's long-term durability endurance test, and oven aging. All seek to expose tires to conditions that cause the type of failures experienced by consumers at 40,000 kilometers or beyond. Because the agency had little data and analysis on either of these tests and understood the tire industry to conduct testing related to the effects of aging on a regular basis, it requested comments on which test would be appropriate for inclusion in the new standard. The tire industry did not, however, include this testing data and analysis in its comments on the NPRM. Further, the agency was unable, in the time period allotted by the TREAD Act, to perform comprehensive testing and analysis of the proposed aging tests and any other alternative tests and parameters. Recently, however, some industry members have begun a dialogue and offered to share data with the agency.
The agency is commencing its own research on tire aging, building on information and data provided by Ford. The agency anticipates publishing a NPRM proposing an aging test, to be included in FMVSS No. 139, in approximately two years.
The final rule also revises FMVSS No. 110 to define Vehicle Normal Load as "no greater than 94% of tire load rating at vehicle placard pressure." FMVSS Nos. 110 and 120 are revised to reflect the applicability of the new standard.
Lastly, the final rule establishes June 1, 2007 as the effective date for all requirements contained herein, for all covered tires and vehicles.
As documented here and in the FRE, the upgraded requirements in the standard specify more stringent and real world, yet practicable, tests that will provide a higher level of operation safety and performance for tires on today's light vehicles.
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B. Summary of Key Differences between NPRM and Final Rule
The major changes to the standard (or deviations from the proposal) are as follows:
(1) Endurance test. The agency is reducing the duration of the endurance test from 40 hours to 34 hours, but extending the final load step from 22 hours to 24 hours. The agency is also reducing the load percentages from 90/100/110% to 85/90/100%.
(2) Low pressure performance test. The agency is adopting the first alternative (endurance) of the low pressure performance tests.
(3) Bead unseating test. The agency is retaining the FMVSS No. 109 bead unseating test for P-metric tires and extending that test to LT tires.
(4) Strength test. The agency is retaining the FMVSS No. 109 strength test for P-metric tires and the FMVSS No. 119 strength test for LT tires.
(5) Aging effects performance test. The agency is deferring adoption of an aging effects performance test until it completes its research and issues a new proposal.
(6) Bias ply tires. The agency is excluding bias ply tires from FMVSS No. 139. Bias ply tires will remain subject to FMVSS No. 109.
(7) Vehicle normal load. The vehicle normal load is defined as "no greater than 94% of tire load rating at vehicle placard pressure."
(8) Ambient temperature. The agency is reducing the ambient temperature in the high speed, endurance, and low pressure performance tests from 40° C to 38° C.
(9) Effective dates/implementation. The agency is providing a 4-year lead time for both tire and vehicle requirements. All covered tires and vehicles must comply with the final rule by June 1, 2007.
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C. Performance Requirements
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1. High Speed Test
The agency is adopting a high speed test for FMVSS No. 139 to be conducted using the following five parameters:
1) Ambient Temperature: 38° C.
2) Load: 85 percent.
3) Inflation Pressure: 220 kPa (32 psi) for standard load p-metric; 260 kPa (38 psi) for extra load p-metric; 320 kPa (46 psi), 410 kPa (60 psi), 500 kPa (73 psi) for LT load ranges C, D, E, respectively.
4) Speed: 140, 150, 160 km/h
5) Duration: 90 minutes total - 30 minutes for each speed.
A tire is deemed to comply with the requirements if, at the end of the high speed test, there is no visual evidence of tread, sidewall, ply, cord, inner liner, or bead separation, chunking, broken cords, cracking, or open splices, and the tire pressure is not less than the initial test pressure. FMVSS No. 109 currently requires a "visual evidence" requirement. "Visual evidence" means visible to the unaided eye.
The agency is adopting a high-speed test with three pre-selected speeds. This testing methodology is different from that in two alternatives that the agency initially considered: 1) GTS-2000, and 2) a high speed test using identical parameters to those proposed above, except that the test speeds are based on the rated speed of the tire (initial test speed (ITS),[25] ITS + 10, ITS + 20, ITS + 30) for durations of 20 minut