The Department of Transportation requires each manufacturer to grade its tires under the Uniform Tire Quality Grade (UTQG) labeling system and establish ratings for treadwear, traction, and temerature resistance. These tests are conducted independently by each manufacturer following goverment guidelines to assign values that represent a comparison between the tested tire and a control tire. While traction and temperature resistance ratings are specific performace levels, the treadwear ratings are assigned by the manufacturers following field testing and are most accurate when comparing tires of the same brand.
Treadwear:
Treadwear receives a comparative rating based on wear rate of the the tire in field testing following a goverment specified course. For example, a tire grade of 150 wears 1.5 times longer than a tire graded 100. Actual performance of the tire can vary significantly depending on conditions, driving habits, care, road characteristics, and climate.
Traction:
Straight-a-head wet braking traction has been represented by a grade of AA, A, B, or C with AA being the highest. Traction grades do not indicate wet cornering ability.
Temperature:
Temperature resistance is graded A, B or C. It represents the tire's resistance to the heat generated by running at high speed. Grade C is the minimum level of performance for all passenger car tires as set under Federal Motor Vehicle Safety Standards. This grade is established for a tire that is properly inflated and not overloaded.
Note: UTQG ratings are not required on winter or light truck (LT) sized tires.