BMW 650i Convertible 2008 - Manual (Page 215)

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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,
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
214 .
M+S
Winter and all-season tires.
These have better winter properties than sum-
mer tires.
Tire condition
Inspect your tires frequently for tread wear,
signs of damage and foreign objects lodged in
the tread, and 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.
Winter tires noticeably loose their suitability for
winter use below a tread depth of 0.16 in/4 mm.
New tires should be mounted in the interest of
safety.
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 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 your speed imme-
diately and have the wheels and tires
inspected immediately. To do this, carefully
drive to the nearest BMW center or a special-
ized tire dealer that works in accordance with
BMW guidelines and uses appropriately trained
personnel. Have the vehicle towed to the repair
shop if necessary. Otherwise, tire damage can
be extremely dangerous to vehicle occupants
and other road users.
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