Mercedes-Benz C-Class (W205) 2015 - 2021 Owners Manual: Tire Quality Grading

In accordance with the US Department of Transportation's "Uniform Tire Quality Grading Standards", tire manufacturers are required to grade their tires on the basis of the following three performance factors:

1. Tread wear grade
2. Traction grade
3. Temperature grade

The data shown in the image is example data.

The classification is not legally stipulated for Canada, but it is generally stated.

Tread wear grade

The tread wear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified test track of the US Department of Transportation.

For example, a tire graded 150 would wear one and one-half times as well on the government test track as a tire graded 100.

The relative 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 practices and differences in road characteristics and climate conditions.

Traction grade

The traction grades - from highest to lowest - are AA, A, B and C. Those grades represent the tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces made of asphalt and concrete.

Temperature grade

The temperature grades are A (the highest), B and C. 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, and excessive temperature can lead to sudden tire failure. Grade C corresponds to a level of performance which all passenger car tires must meet under the requirements of the US Department of Transportation.