Saab 2007 owner manual Uniform Tire Quality Grading, Treadwear 200 Traction AA Temperature a

226 Car care and technical information

Uniform Tire Quality Grading

Quality grades can be found where applica- ble on the tire sidewall between tread shoul- der and maximum section width. For exam- ple:

Treadwear 200 Traction AA

Temperature A

The following information relates to the system developed by the United States National Highway Traffic Safety Administra- tion, which grades tires by treadwear, trac- tion and temperature performance. (This applies only to vehicles sold in the United States.) The grades are molded on the side- walls of most passenger car tires. The Uni- form 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-pro- duction tires.

While the tires available on General Motors passenger cars and light trucks may vary with respect to these grades, they must also conform to federal safety requirements and additional General Motors Tire Perfor- mance Criteria (TPC) standards.

Treadwear

The treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test course. For example, a tire graded 150 would wear one and a half (1.5) times as well on the govern- ment course as a tire graded 100. The rela- tive performance of tires depends upon the actual conditions of their use, however, and may depart significantly from the norm due to variations in driving habits, service prac- tices and differences in road characteristics and climate.

Traction – AA, A, B, C

The traction grades, from highest to lowest, are AA, A, B, and C. Those grades repre- sent the tire’s ability to stop on wet pave- ment as measured under controlled condi- tions on specified government test surfaces of asphalt and concrete. A tire marked C may have poor traction performance. Warn- ing: The traction grade assigned to this tire is based on straight-ahead braking traction tests, and does not include acceleration, cornering, hydroplaning, or peak traction characteristics.

Temperature – A, B, C

The temperature grades are A (the highest), B, and C, representing the tire’s resistance to the generation of heat and its ability to dis- sipate 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, and excessive temper- ature can lead to sudden tire failure. The grade C corresponds to a level of perfor- mance which all passenger car tires must meet under the Federal Motor Vehicle Safety Standard No. 109. Grades B and A represent higher levels of performance on the laboratory test wheel than the minimum required by law.

Warning: The temperature grade for this tire is established for a tire that is properly inflated and not overloaded. Excessive speed, underinflation, or excessive loading, either separately or in combination, can cause heat buildup and possible tire failure.