The 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 400 the tread would last two times longer than graded 200.
The 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. Tires marked AA has excellent traction performance and tires marked C may have poor traction performance.
The temperature grades are A (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. Sustained high temperature can cause the material of the tire to de- generate and reduce tire life, and excess temperature can lead to sudden tire failure. The grade C corresponds to a level of performance which all passenger car tires must meet under the Federal Motor Vehicle Safety Standard # 109. Grades B and A represent higher levels of performance on the laboratory test wheel than the minimum required by law.