Bmw 01 41 0 155 307 Bedienungsanleitung PDF herunterladen (Seite 125)

125n

Index Data Technology Repairs Car care Controls Overview

To maintain good handling and vehicle

response, use only tires of a single

tread configuration from a single manu-

facturer. BMW tests and approves

wheel/tire combinations. Refer to

page 129.

DOT Quality Grades

Treadwear

Traction AA A B C

Temperature A B C

All passenger car tires must

conform to Federal 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 condi-

tions on a specified government test

course.

For example, a tire graded 150 would

wear one and one-half (1g) times as

well on the government course as a tire

graded 100. The relative performance

of tires depends upon the actual condi-

tions of their use, however, and may

depart significantly from the norm due

to variations in driving habits, service

practices and differences in road char-

acteristics and climate.

Traction

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 speci-

fied government test surfaces of asphalt

and concrete. A tire marked C may have

poor traction performance.

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 charac-

teristics.<

Temperature

The temperature grades are A (the

highest), B, and C, representing the

tire's resistance to the generation of

heat and its ability to dissipate heat

when tested under controlled condi-

tions 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 Stan-

dard No. 109. Grades B and A repre-

sent higher levels of performance on

the laboratory test wheel than the

minimum required by law.

The temperature grade for this tire

is established for a tire that is

properly inflated and not overloaded.

Excessive speed, under-inflation, or

excessive loading, either separately or

in combination, can cause heat buildup

and possible tire failure.<

Uniform Tire Quality Grading

Quality grades can be found where

applicable on the tire sidewall between

tread shoulder and maximum section

width. For example:

Tread wear 200 Traction AA

Temperature A

Do not use retreaded tires. Driving

safety may be impaired by their

use. This is due to the possible varia-

tions in casing structures and, in some

cases, to their extreme age, which can

lead to a decrease in their durability.<

Tire replacement

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