DEPARTMENT OF TRANSPORTATION UNIFORM TIRE QUALITY GRADES

The following tire classification categories were established by the National Highway Traffic Safety Administration. The specific rating is assigned by the tire manufacturer and is shown in each category on the sidewall of the tires for your vehicle.

All passenger car tires must conform to Federal safety requirements in addition to these grades.

Sport Utility

Treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test course. For example, a tire graded 150 will wear one and one-half times as well on the government course as a tire graded 100. The relative performance of tires depends on actual use conditions, however, and may vary significantly from the norm due to differences in driving habits, service practices, and differences in road characteristics and climate.

Traction Grades

Traction grades, from highest to lowest, are AA, A, B, and C. These grades represent the tire's ability to stop on wet pavement, as measured under controlled conditions on specified government test surfaces of asphalt and concrete. A tire marked C may have poor traction performance.

Temperature Grades

Temperature grades: A (the highest), B, and C, representing the tire's resistance to the generation of heat and its ability to dissipate heat, when tested under controlled conditions on a specified indoor laboratory test wheel.

Sustained high temperature can cause the tire material to degenerate and reduce tire service life, and excessive temperature may lead to sudden tire failure. Grade C corresponds to a performance level that all passenger car tires must meet under Federal Motor Vehicle Safety Standard No. 109. Grades B and A represent higher levels of performance on the laboratory test wheel than the minimum required by law.