Tire condition – BMW Z4 Roadster 2.5i 2005 User Manual
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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 Vehi-
cle 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 excessive loading, either
separately or in combination, can cause heat
buildup and possible tire failure.
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RSC: Run Flat tires
Run Flat tires are labeled on the sidewall with a
circular symbol containing the letters RSC.
Refer to page
M+S
Winter and all-season tires.
These have better winter performance proper-
ties than summer tires.
Tire condition
Inspect your tires frequently for tread wear,
signs of damage and for foreign objects lodged
in the tread. Check the tread depth.
Tire tread
Tread depth should not be allowed to go below
1/8 in / 3 mm even though in Europe, for exam-
ple, the legally specified minimum tread depth
is only 1/16 in / 1.6 mm. Below 1/8 in / 3 mm
tread depth, there is a very high risk of hydro-
planing, even with only small amounts of water
on the road and at relatively moderate speeds.
At tread depths below approx. 1/6 in / 4 mm,
winter tires display a perceptible decrease in
their ability to cope with winter driving condi-
tions, and should be replaced in the interest of
safety.
Tread wear indicators in the tread-groove base,
see arrow, are distributed around the wheel cir-
cumference and are labeled on the tire sidewall
as TWI, Tread Wear Indicator. At a tread depth
of 1/16 in / 1.6 mm, the indicators signal that the
legally permissible wear limit has been reached.
Wheel/tire damage
Due to low-profile tires, please note that
wheels, tires and suspension parts are
more susceptible to road hazards and conse-
quential damages.
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Unusual vibrations encountered during normal
vehicle operation can indicate tire failure or
some other vehicle malfunction. This type of
problem can be caused by contact with curbs,
etc. This is also true for irregularities in the vehi-
cle's handling characteristics, such as a pro-
nounced tendency to pull to the left or right.
Should this occur, respond by immedi-
ately reducing your speed. Proceed care-
fully to the nearest BMW center or professional
tire center, or have the vehicle towed there.
Tire damage up to and including sudden and
complete air loss can pose an extreme hazard
for both vehicle occupants and other road
users.
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