USA: NHTSA final rule on standard reference test tire (SRTT)
The National Highway Traffic Safety Administration (NHTSA) of the Department of Transportation (DOT) has published a final rule that amends several Federal motor vehicle safety standards and consumer information regulations to update the standard reference test tire (SRTT) used therein.
The SRTT is used in those standards and regulations as a baseline tire to rate tire treadwear, define snow tires based on traction performance, and evaluate pavement surface friction. This rule is necessary because the only manufacturer of the currently referenced SRTT ceased production of the tire. Referencing a new SRTT ensures the availability of a test tire for testing purposes.
The 14-inch SRTT is used by NHTSA in three ways. First, as part of the Federal Motor Vehicle Safety Standards (FMVSS) (49 CFR part 571), it is used to verify the surface friction of test surfaces for braking and electronic stability control standards.
Second, it is used as a traction reference for the determination of whether a tire may be considered a ‘‘snow tire’’ under FMVSS No. 139 (49 CFR 571.139). Third, the SRTT is used in NHTSA’s Uniform Tire Quality Grading Standards (UTQGS) consumer information program as the course reference tire as part of NHTSA’s base course wear rating (BCWR) determination for the treadwear course.
Because Michelin, the only manufacturer of the 14-inch SRTT, has ceased production of the tire in 2020, NHTSA must find a suitable replacement tire. After substantial testing by NHTSA and several test partners, NHTSA has determined that the 16-inch SRTT is a suitable replacement. The testing program has determined equivalent values for test surface friction, the snow tire determination, and the BCWR determination that do not change the severity of any requirements and ensure that tire consumer ratings tested using either SRTT are comparable.
The effective date of this final rule is 8 July 2022. Petitions for reconsideration of this final rule and public comments on it must be received not later than 25 July 2022.
The final rule can be accessed HERE.