Tire Rating Criteria:
1) Uniform Tire Quality Grade (UTQG)
A compulsory grading system for summer and all season tires sold in North America. The UTQG provides comparative manufacturer information. Tires are subjected to a series of government tests that measure performance in treadwear, traction, and temperature resistance.
2) Temperature Resistance
This unit provides a measure of resistance to heat generation under normal operating conditions. The test is conducted under predetermined standards for inflation and loading. Excessive speed, under inflation, and overloading can all cause adverse heat build up. Sustained high temperatures can reduce tire durability. Resistance tire grades are branded on the sidewall rated with either AA, A, B, or C.
Resistance Grade A: The maximum performance level indicating the tire withstood a half hour run at 185 km/h (115 mph) without failing.
Resistance Grade B: The tire passed 160 km/h (100 mph), but not 185 km/h (115mph).
Resistance Grade C: The minimum performance level indicating that the tire failed to complete a half hour at 160 km/h (100mph).
Traction is a measurement of a tire’s ability to stop in a straight line on wet test surfaces of asphalt and concrete. Traction grades are assigned by the UTQG system and branded on the sidewall. Traction tire grades are branded on the sidewall rated with either AA, A, B, or C.
Traction Grade A: The tire performed well on both surfaces.
Traction Grade B: The tire performed well on al least one of the two surfaces.
Traction Grade C: The tire performed poorly on one or both of the two surfaces.
Tire Speed Ratings:
Speed ratings are certified maximum sustained speed designations assigned to passenger car radials and high performance tires. Because of the evolution of high-speed passenger car travel, it was necessary to establish a way to rate a tire’s high-speed capability. As vehicles have increased their top speeds into Autobahn-only ranges, the tire speed ratings have evolved to better identify the tires capability, allowing drivers to match the speed of their tires with the top speed of their vehicle.
The International Standard Organization system (ISO) currently serves as a worldwide standard for tire markings.