Wheels and tires, Uniform tire quality grading standards – Mercedes-Benz SLK-Class 2012 Owners Manual User Manual

Page 310

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The actual values for tires are vehicle-

specific and may deviate from the values in

the illustration.

Where applicable, the tire grading

information can be found on the tire sidewall

between the tread shoulder and maximum

tire width.
For example:

Tread wear Traction Temperature
200

AA

A

All passenger car tires must conform to the

statutory safety requirements in addition to

these grades.

Tread wear

The tread wear grade is a comparative rating

based on the wear rate of the tire when tested

under controlled conditions on a specified

U.S. government course. For example, a tire

graded 150 would wear one and one-half

times as well on the government course 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

G

WARNING

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.

The traction grades, from highest to lowest,

are AA, A, B, and C. Those grades represent

the tire's ability to stop on a wet surface as

measured under controlled conditions on

specified government test surfaces of asphalt

and concrete. A tire marked C may have poor

traction performance.
The safe speed on a wet, snow covered or icy

road is always lower than on dry road

surfaces.
You should pay special attention to road

conditions when temperatures are around

the freezing point.
Mercedes-Benz recommends a minimum

tread depth of ã in (4 mm) for all four winter

tires (

Y

page 296) to maintain normal driving

characteristics in winter. Winter tires can

reduce the braking distance on snow-covered

surfaces in comparison with summer tires.

Stopping distance, however, is still

considerably greater than when the road is

not covered with ice or snow. Take

appropriate care when driving.

!

Avoid wheelspin. This can lead to damage

to the drive train.

Temperature

G

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

excessive heat build-up and possible tire

failure.

The temperature grades are A (the highest),

B, and C. These 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. 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. Grades B and A

308

Uniform Tire Quality Grading Standards

Wheels

and

tires

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