BMW M COUPE Manual page 112

Tire replacement
112n
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
properly inflated and not overloaded.
Excessive speed, under-inflation, or ex-
cessive loading, either separately or in
combination, can cause heat buildup
and possible tire failure.<
Uniform Tire Quality Grading
Quality grades can be found where ap-
plicable 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 as this
could negatively affect driving
safety. This is 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 age
The date on which the tire was manu-
factured is indicated by the code on the
sidewall:
DOT ... 109 indicates that the tire was
manufactured in Week 10 of 1999.
BMW recommends the replacement of
all tires when the tires are no more than
6 years old, even if a tire life of 10 years
is possible.
Spare tires over 6 years old should be
used only in case of emergency. A tire
of this age should be replaced by a new
tire immediately, and should not be
fitted together with new tires.
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