BMW 528I User Manual download pdf (Page 135)

135n

RepairsIndex OverviewControlsCar careTechnologyData

Tire replacement

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 137.

DOT Quality Grades

Treadwear

Traction AA A B C

Temperature A B C

All passenger car tires must con-

form to Federal Safety Require-

ments in addition to these grades.<

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 cha-

racteristics 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, cornering, hydro-

planing, or peak traction characteri-

stics.<

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 tem-

perature 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 Mo-

tor 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 pro-

perly inflated and not overloaded. Ex-

cessive speed, underinflation, or exces-

sive loading, either separately or in

combination, can cause heat buildup

and possible tire failure.<

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