Uniform Tire Quality Grading

The UTQG was created by the National Highway Traffic Safety Administration in 1978, a branch of the United States Department of Transportation (DOT).

The National Highway Traffic Safety Administration (NHTSA) established the Uniform Tire Quality Grading Standards (UTQGS) in 49 CFR 575.104.

The NHTSA published DOT HS 812 325 “Consumer Guide to Uniform Tire Quality Grading” August 2016, which provides rating information.

[5] Non-passenger car tires, such as those for motorcycles, buses, medium trucks and above along with trailers are also not required to have a UTQG rating, although FMVSS Standard 109 requires the following to be listed on the tire's sidewall: speed restriction if less than 55 mph, regroovable if designed for regrooving, and a letter designating load range rating.

CMT tires are now "specially designed and built to American Society for Testing and Materials (ASTM) standard E1136 to have particularly narrow limits of variability."

This relationship can be represented by the following formula:[7] Generally speaking, a lower treadwear rating correlates with a higher friction coefficient and thus provides a shorter braking distance.

However, this is an average rule, and for the same friction coefficient, the curve in this study shows large variations in treadwear rating, which decrease the significance of this relationship.

Thus, depending on production method and tire model, the quality of rubber (thanks to certain additives) can multiply the treadwear rating by more than 3 without lessening the friction coefficient.

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

The test tire is installed on an instrumented axle of a traction trailer, which is towed by a truck at 40 miles per hour (mph) over wet asphalt and concrete surfaces.

The brakes, from the test tire only, are momentarily locked, and sensors on the axle measure the longitudinal and vertical forces as it slides in a straight line.

As braking torque increases, the tire deforms more and tread elements near the rear of the contact patch with the road begin to slip rather than grip.