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Wheels and tires
172
Tire replacement
To maintain good handling and vehicle
response, use only tires of a single tread
configuration from a single manufacturer.
BMW tests and approves specific wheel
and tire combinations.
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.<
Treadwear
The treadwear grade is a comparative
rating based on the wear rate of the tire
when tested under controlled conditions
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 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.
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 specified govern-
ment 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 characteristics.<
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 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 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 properly
inflated and not overloaded. Excessive
speed, underinflation, or excessive
loading, either separately or in combina-
tion, can cause heat buildup and possible
tire failure.<
Uniform Tire Quality Grading
Quality grades can be found where appli-
cable on the tire sidewall between tread
shoulder and maximum section width. For
example:
Treadwear 200 Traction AA
Temperature A
Do not use retreaded tires, since
driving safety may be impaired.
Possible variations in the design and the
age (which could be substantial) of the
carcasses can lead to unusually rapid
wear.<
Tire age
The tire's date of manufacture is indicated
on the sidewall:
DOT ... 4901 indicates that a tire was
manufactured in week 49 of the year 2001.
Regardless of milage or wear, BMW
recommends that you replace all tires –
including the spare tire – after a maximum
of 6 years, even though the tires may have
a theoretical service life of up to 10 years.
Online Edition for Part No. 01400156097 – © 10/01 BMW AG
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