BMW 745I - Manual (Page 188)

Wheels and tires
186
Tire condition
Tire tread – tire damage
Inspect your tires frequently for tread wear,
signs of damage and for foreign objects
lodged in the tread. Check the tread depth.
The tread depth should not drop below
0.12 in (3 mm), although, for example,
European legislation only specifies a
minimum tread depth of 0.06 in (1.6 mm).
At tread depths below 0.12 in (3 mm) there
is an increased risk of high-speed hydro-
planing, even when only small amounts of
water are present on the road surface.
Wear indicators at the tread-groove base,
see arrow, are distributed over the tire's
circumference and are marked on the tire
sidewall with TWI – Tread Wear Indicator.
These indicators signal at a tread depth of
0.06 in (1.6 mm) that the legal wear limit
has been reached.
Never attempt to continue driving on
a flat tire. Because a flat tire will
seriously impair your vehicle's handling
and braking response, attempts to drive on
a flat tire can lead to loss of control over the
vehicle.
To avoid loading the tires beyond their
approved carrying capacity, never overload
the vehicle. Overloading can lead to over-
heating and damage inside the tires. The
ultimate result can assume the form of a
sudden air loss.
Unusual vibrations encountered during
normal vehicle operation can indicate tire
failure or some other vehicle defect. This
can, for example, 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. Should this occur,
respond by immediately reducing your
speed. Carefully proceed – or have your
vehicle towed – to the nearest BMW center
or tire dealer to have the wheels or tires
inspected.
Tire damage, extending to sudden and
complete loss of pressure in extreme
cases, can pose a potentially lethal safety
hazard for the vehicle's occupants and
other road users alike.
<
Run-flat tires*
Run-flat tires consist of self-contained tires
and special rims. The tire reinforcement
ensures that the tire retains some residual
safety in the event of pressure drop and
driving remains possible to a restricted
degree, refer to page
200 .
The vehicle is equipped with a Flat Tire
Monitor or TPM Tire Pressure Monitor
which indicates flat tires.
Tire replacement
To maintain good handling and vehicle
response, use only tires of a single tread
configuration from a single manufacturer.
BMW tests and approves specific wheel
and tire combinations.
DOT Quality Grades
Treadwear
Traction AA A B C
Temperature A B C
All passenger car tires must conform
to Federal Safety Requirements in
addition to these grades. <
Treadwear
The treadwear grade is a comparative
rating based on the wear rate of the tire
when tested under controlled conditions
on a specified government test course.
For example, a tire graded 150 would
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