Legal Minimum Tread Depth for Passenger Car Tires in the U.S.A.: A Survey

Le résumé fourni par la source

Vehicle tire-roadway friction on dry, clean roads is essentially independent of tread depth, and depends primarily on roadway surface texture. However, when the roads are wet, adequate tire-roadway friction (both for longitudinal braking and lateral cornering forces), depends on several variables, including water depth, speed and tire tread depth, and the roadway surface texture. A variable that can be controlled by drivers is their vehicles' tire tread. This article presents the results from a survey of state requirements for legal minimum tread depth for passenger vehicle tires in the United States. Most states require a minimum of 2/32 of an inch (approximately 1.6 mm) of tread, but two require less, some have no requirements, and some defer to the federal criterion for commercial vehicle safety inspections. The authors note that research indicates that a minimum tread depth of 2/32 of an inch does not prevent significant loss of friction at highway speeds, even for minimally wet roadways. Tires with less than 4/32 of an inch tread depth may lose approximately 50 percent of available friction in those circumstances, even before hydroplaning occurs. The authors conclude that the present requirements for minimum passenger car tire tread depth are not based upon rational safety considerations, and that an increase in the minimum tread depth requirements would have a beneficial effect on highway safety.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.