BMW SERIE 3 CONVERTIBLE 2000 Bedienungshandbuch PDF herunterladen (Seite 124)

124n

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 128.

DOT Quality Grades

Treadwear

Traction AA A B C

Temperature A B C

In addition to the tire grades listed

above, all passenger car tires must

conform to Federal Safety Require-

ments as well.<

Treadwear

The treadwear 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 (1-1/2) 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

characteristics 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 as-

phalt 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, corner-

ing, hydroplaning, or peak traction

characteristics.<

Temperature

The temperature grades are A (the high-

est), B, and C, representing the tire's re-

sistance to the generation of heat and

its ability to dissipate heat when tested

under controlled conditions on a speci-

fied indoor laboratory test wheel.

Sustained high temperature can cause

the tire material to degenerate and re-

duce tire life, and excessive tempera-

ture can lead to sudden tire failure. The

Grade C corresponds to a level of per-

formance 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.

The temperature grade for this tire

is established for a tire that is prop-

erly inflated and not overloaded. Exces-

sive speed, underinflation, or excessive

loading, either separately or in combina-

tion, can cause heat buildup and possi-

ble 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 ("caps").

Driving safety may be impaired by

their use. This due to the possible varia-

tions in casing structures and, in some

cases, to their extreme age, factors

which can lead to a decrease in their

durability.<

Tire replacement

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