1996 Chevrolet Corvette Owner's Manual - Page 282

Uniform Tire Quality Grading The following information relates to the system developed by the United States National Highway Traffic Safety Administration, which grades tires by treadwear, traction and temperature performance. (This applies only to vehicles in the United States.) The sold grades are molded on the sidewalls of most passenger car tires. The Uniform Tire Quality Grading system does not apply to deep tread, winter-type snow tires, space-saver or temporary use spare tires, tires with nominal rim diameters of 10 to 12 inches(25 to 30 cm), or to some limited-production tires. While the tiresavailable on General Motors passenger cars andlight trucks may vary with respect to these grades, they must alsoconform to Federal safety requirements andadditional General Motors Tire Performance Criteria (TPC) standards. upon the actual conditions of their use, however, and may depart significantly from thenorm due tovariations in drivinghabits, service practices and differences in road characteristics and climate. Traction A, B, C The traction grades, from highest to lowest, A, B, and are C , and they represent the tire's ability to stop wet on pavement as measured under controlled conditions on specified government test surfacesof asphalt and concrete. A tire marked C may have poor traction performance. Warning: The traction grade assigned to this tire is based on braking (straightahead) traction tests and does not include cornering(turning) traction. - Temperature A, B, C The temperaturegrades are A (the highest), B, and C, representing the tire's resistance to the generationof heat and its ability to dissipate heat when tested under controlled conditionson a specified indoor laboratory test wheel. Sustainedhigh temperature can cause the material of the tire to degenerate and reduce tire life, and excessive temperature can lead to ,suddentire failure. The grade C corresponds to a level of performance which all passenger car tires must meet under the Federal Motor Vehicle Safety Standard No. 109. - Treadwear The treadwear grade a comparative rating based on is the wear rateof the tire when tested under controlled conditions ona specified government test course. For example, a tire graded 150 would wear one and a half (1 1/2) times as well on the government course as a tire graded 100. The relative performance of tires depends 6-51