2433 Arlington Street
Pittsburgh, PA 15209
Dear Mr. Obrycki:
This responds to your January 16, 1996 letter to this agency suggesting that tire safety would be improved if we were to require a yellow line approximately 1/4 of an inch wide across the width of tires at the 3/32 of an inch tread depth level. You stated that such a requirement could enable consumers to tell when tires are unsafe and could enable state police and inspection stations to readily observe dangerous tread levels. You believe that this would enhance passenger safety because worn tires would be replaced sooner.
We have carefully reviewed your letter, but do not agree that the requirement you suggest is warranted at this time. Our decision is explained below.
By way of background information, the National Highway Traffic Safety Administration (NHTSA) has the authority to issue Federal motor vehicle safety standards (FMVSSs) applicable to the manufacture and sale of new motor vehicles and new items of motor vehicle equipment. Among other things, such standards must be reasonable, practicable, and appropriate for the particular type of motor vehicle or motor vehicle equipment for which they are prescribed. Once a vehicle or item of equipment is sold to the consumer, NHTSA's authority generally terminates and with certain exceptions, use of that vehicle or item of equipment then becomes a matter of state jurisdiction.
NHTSA has issued a number of FMVSSs and related regulations applicable to tires, the pertinent ones here being FMVSS Nos. 109, New pneumatic tires, and 119, New pneumatic tires for vehicles other than passenger cars. Both standards require that all tires have treadwear indicators molded into the tread at the 2/32 of an inch tread depth level. This level was selected by NHTSA based on early studies that showed that when tread is worn to 2/32 of an inch, a tire rapidly loses its traction characteristics, thereby becoming unsafe. Although states, not NHTSA, have the authority to enforce tire removal when the tread depth becomes worn below a certain level, the agency has issued vehicle in use inspection standards at 49 Code of Federal Regulations, Part 570, for states to use as a guide in establishing their own vehicle inspection requirements.
You stated in your letter that Pennsylvania, and perhaps other states, has established minimum tread depth requirements at 3/32 of an inch. The state has the authority to do that, since it has jurisdiction over the use of vehicles and equipment. NHTSA has retained the 2/32 of an inch requirement for tread depth indicators, however, and recently denied a petition to raise the tread depth indicators to 3/32 of an inch because there was no proven safety need to do so. A copy of the denial notice is enclosed.
Although NHTSA has the authority to require a yellow line across the tire to highlight the tread depth indicators, the agency has no data suggesting a safety need for such action. The tread depth indicators currently required, even though unobtrusive from a distance, have been shown to be effective in alerting motorists, inspection stations, and law enforcement personnel to unsafe tire wear. Accordingly, without further data showing a safety need to do so, NHTSA does not believe that requiring yellow tread wear markings in addition to those already required would be reasonable at this time.
Thank you for your interest in motor vehicle safety.
Samuel J. Dubbin Chief Counsel