BMW 750i Sedan 2006 - Manual (Page 200)

Wh
eels
and
tire
s
198
Temperature
The temperature grades are A, B, and C, A
being highest, and represent the tire's resis-
tance 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,
underinflation, or excessive loading, either sep-
arately or in combination, can cause heat
buildup and possible tire failure.
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RSC Run-flat tires
You will recognize run-flat tires by a circular
symbol containing the letters RSC on the side
of the tire, refer to page
199 .
M+S
Winter and all-season tires.
These have better winter properties than sum-
mer tires.
XL
Indicates specially reinforced tires.
Tire condition
Inspect your tires frequently for tread depth,
signs of damage and for foreign objects lodged
in the tread. Check the tread depth.
Minimum tread depth
The tread depth should not fall below 0.12 in/
3 mm, although, for example, European legisla-
tion only specifies a minimum tread depth of
0.063 in/1.6 mm.
At tread depths below 0.12 in/3 mm, there is an
increased risk of high-speed hydroplaning,
even when only small amounts of water are
present on the road surface.
Winter tires display a noticeable loss in their
ability to cope with cold-weather driving condi-
tions once the tread wears to below 0.16 in/
4 mm. To ensure continued safety, you should
always have such tires replaced.
Wear indicators at the tread-groove base, refer
to arrow, are distributed over the tire's circum-
ference and are marked on the side of the tire
with TWI – Tread Wear Indicator. If the tire tread
has been driven down to the wear indicators, a
tread depth of 0.063 in/1.6 mm has been
reached.
Wheel/tire damage
Please note that low profile tires make wheels,
tires, and suspension parts more susceptible to
road hazards and consequential damages.
Unusual vibrations encountered during normal
vehicle operation can indicate tire failure or
some other vehicle defect. This can, for exam-
ple, be caused by driving over curbs. These
kinds of problems may also be signaled by other
changes in vehicle response, such as a strong
tendency to pull to the left or right.
In these cases, reduce speed immedi-
ately and have wheels and tires thor-
oughly checked. Drive carefully to the nearest
BMW center or tire shop that works according
to BMW repair procedures with correspond-
ingly trained personnel. If necessary, have the
vehicle towed there.
Tire damage can be extremely dangerous for
vehicle occupants and other road users.
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