BMW X6 xDrive50i 2008 - Manual (Page 238)

Wh
eels
and
tire
s
236
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
237 .
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 wear,
signs of damage and for foreign objects lodged
in the tread. Check the tread depth.
Minimum tread depth
The tread depth should not drop 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.
When winter tires wear down past a tread depth
of 0.16 in/4 mm, they become perceptibly less
suitable for winter conditions. For the sake of
safety, new tires should be installed.
Wear indicators at the tread-groove base are
distributed over the tire's circumference 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 cause wheels,
tires and suspension parts to be more suscep-
tible to road hazards and consequential dam-
ages.
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. To do so, drive carefully to the
nearest BMW Sports Activity Vehicle Center or
tire shop that works according to BMW repair
procedures with correspondingly trained per-
sonnel. If necessary, have the vehicle towed
there. Otherwise, tire damage can be extremely
dangerous to vehicle occupants and other road
users.
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