Tire Ratings

Treadwear:
Treadwear ratings range from a low value of 60 to over 500. These ratings indicate the relative performance of tires under standards conditions. Actual performance is dependent upon a number of factors, including driving habits, road characteristics, climate, etc. Treadwear values can be used to estimate number of miles the tire will last using the following formula: multiply the rating by two, the add two zeros to the answer. For example, a rating of 300 means the tire should last about 60,000 miles.

Traction:
Traction ratings range from the highest to lowest in the following ranking: AA, A, B, C. This rating system is measure of the tire’s ability to stop on wet concrete and asphalt.

Temperature:
Temperature ratings range from the highest to lowest in the following ranking: A, B, C, and are a measure of the tire’s ability to withstand high temperatures. High temperatures may lead to sudden tire failure, and are caused by a number of driving conditions.

See also:
http://www.nhtsa.dot.gov/cars/rules/regrev/evaluate/807805.html