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 The Uniform Tire Quality Grading is a labeling system required by the federal government. All tires sold in the United States must be graded and labeled with information on treadwear, temperature (resistance to heat buildup) and traction. These ratings are intended to help consumers more easily compare tires. Tires sold in the United States must be examined through a series of tests defined by the government and conducted by the manufacturer. Manufacturers are then responsible for assigning ratings to their products.
TREADWEAR
The treadwear grade is based on a 7,200-mile wear test conducted under controlled conditions on a standard test course. Tires are measured for wear, and the life expectancy is extrapolated to wear-out, which is 2/32 inch of tread. Tire manufacturers grade their tires based on this standard test. The higher the grade, the longer the expected tire life. Treadwear gradings are given in numbers. For example, a tire graded 300 would wear twice as long on the standard test course as a tire graded 150. The relative performance of tires depends upon the actual conditions of their use, however, and may depart significantly from the norm due to differences in road characteristics and climate.
TRACTION
Traction grades are A, B and C, with A being highest. The rating is based on a low-speed (40 mph) wet braking test and generally indicates the traction capability of the tread compound in straight-ahead braking. Due to the low speed and relatively rough test surface, results are not greatly affected by tread patterns. Also, the grade does not indicate the tire's relative ability to generate cornering force or to resist hydroplaning.
TEMPERATURE
The temperature grades are A (the highest), B, and C, and they represent the tire's resistance to the generation of heat and its ability to dissipate heat when tested under controlled conditions on a specified indoor laboratory test wheel. Sustained high temperature can cause the material of the tire to degenerate and reduce tire life. Excessive temperature can lead to sudden tire failure. The grade C corresponds to a level of performance that all passenger car tires must meet under the Federal Motor Vehicle Safety Standard No. 109. Grades A and B represent higher levels of performance on the laboratory test wheel than the minimum required by law.
WARNING: The temperature grade for each tire is established for a tire that is properly inflated and loaded. Excessive speed, under inflation, excessive loading, either separately or in combination, can cause heat buildup and possible tire failure.
IMPORTANT: Tire grade designations are required by government regulations for comparison purposes only. |
