DEPARTMENT OF TRANSPORTATION UNIFORM TIRE QUALITY GRADES

The following tire classification grades have been established by the National Highway Traffic Safety Administration. The specific grade assigned by the tire manufacturer for each category is molded on the sidewall of your vehicle's tires.

In addition, all passenger car tires must conform to Federal safety requirements in addition to these grades.

Sport Utility

Treadwear is a comparative rating based on the wear rate of a tire when tested under controlled conditions on a specified government test course. For example, a tire graded 150 would wear one and one-half times as well on the government course as a tire graded 100. Relative performance of tires depends, however, upon the actual conditions of their use and may differ significantly from the norm due to variations 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, measured under controlled conditions on government-specified asphalt and concrete test surfaces. A tire marked C may have poor traction performance.

Temperature Grades

Temperature grades are 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 material of the tire to degenerate and reduce tire life, and excessive temperature can lead to sudden tire failure. The C grade corresponds to a level of performance 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.