Uniform Tire Quality GradingQuality grades can be found where applicable on thetire sidewall between tread shoulder and maximumsection width. For example:Treadwear 200 Traction AA Temperature AThe following information relates to the systemdeveloped by the United States National HighwayTraffic Safety Administration, which grades tires bytreadwear, traction and temperature performance. (Thisapplies only to vehicles sold in the United States.)The grades are molded on the sidewalls of mostpassenger car tires. The Uniform Tire Quality Gradingsystem does not apply to deep tread, winter-typesnow 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 tires available on General Motors passengercars and light trucks may vary with respect to thesegrades, they must also conform to federal safetyrequirements and additional General Motors TirePerformance Criteria (TPC) standards.TreadwearThe treadwear grade is a comparative rating based onthe wear rate of the tire when tested under controlledconditions on a specified government test course.For example, a tire graded 150 would wear one anda half (1.5) times as well on the government course asa tire graded 100. The relative performance of tiresdepends upon the actual conditions of their use,however, and may depart significantly from the normdue to variations in driving habits, service practices anddifferences in road characteristics and climate.Traction – AA, A, B, CThe traction grades, from highest to lowest, are AA, A,B, and C. Those grades represent the tire’s abilityto stop on wet pavement as measured under controlledconditions on specified government test surfaces ofasphalt and concrete. A tire marked C may have poortraction performance. Warning: The traction gradeassigned to this tire is based on straight-ahead brakingtraction tests, and does not include acceleration,cornering, hydroplaning, or peak traction characteristics.5-74
