Uniform Tire Quality GradingQuality grades can be found where applicableon the tire sidewall between tread shoulderand maximum section width. For example:Treadwear 200 Traction AA Temperature AThe following information relates to the systemdeveloped by the United States NationalHighway Traffic Safety Administration (NHTSA),which grades tires by treadwear, traction, andtemperature performance. This applies onlyto vehicles sold in the United States. The gradesare molded on the sidewalls of most passengercar tires. The Uniform Tire Quality Grading(UTQG) system does not apply to deep tread,winter-type snow tires, space-saver, or temporaryuse spare tires, tires with nominal rim diametersof 10 to 12 inches (25 to 30 cm), or to somelimited-production tires.While the tires available on General Motorspassenger cars and light trucks may vary withrespect to these grades, they must also conformto federal safety requirements and additionalGeneral Motors Tire Performance Criteria (TPC)standards.TreadwearThe treadwear grade is a comparative rating basedon the wear rate of the tire when tested undercontrolled conditions on a specified governmenttest course. For example, a tire graded 150 wouldwear one and a half (1.5) times as well on thegovernment course as a tire graded 100. Therelative performance of tires depends upon theactual conditions of their use, however, and maydepart significantly from the norm due to variationsin driving habits, service practices, and differencesin road characteristics and climate.Traction – AA, A, B, CThe traction grades, from highest to lowest, areAA, A, B, and C. Those grades represent the tire’sability to stop on wet pavement as measured undercontrolled conditions on specified government testsurfaces of asphalt and concrete. A tire marked Cmay have poor traction performance.Warning: The traction grade assigned to thistire is based on straight-ahead braking tractiontests, and does not include acceleration, cornering,hydroplaning, or peak traction characteristics.468
