160Vehicle care9Warning
For specific tyres the
recommended tyre pressure as
shown in the tyre pressure table may exceed the maximum tyre
pressure as indicated on the tyre.
Never exceed the maximum tyre
pressure as indicated on the tyre.
If the tyre pressure must be reduced
or increased on a vehicle with tyre
pressure monitoring system, switch
off ignition.
Temperature dependency
The tyre pressure depends on the
temperature of the tyre. During
driving, tyre temperature and
pressure increase. Tyre pressure
values provided on the tyre
information label and tyre pressure
chart are valid for cold tyres, which means at 20 °C.
The pressure increases by nearly
1.5 psi for a 10 °C temperature
increase. This must be considered
when warm tyres are checked.
Tyre pressure monitoring
system
The tyre pressure monitoring system
uses radio and sensor technology to
check tyre pressure levels.Caution
Tyre pressure monitoring system
warns only about low tyre pressure condition and does not replace
regular tyre maintenance by the
driver.
The tyre pressure monitoring system sensors monitor the air pressure in
the tyres and transmit tyre pressure
readings to a receiver located in the
vehicle.
All wheels must be equipped with
pressure sensors and the tyres must
have the prescribed pressure.
Tyre pressure chart 3 190.
Notice
In countries where the tyre pressure
monitoring system is legally
required, the use of wheels without
pressure sensors will invalidate the
vehicle type approval.
Low tyre pressure condition
A detected low tyre pressure
condition is indicated by illumination
of control indicator w 3 86 together
with a warning chime. In vehicles with Multifunction version of the Driver
Information Centre, a corresponding message is also displayed.
Vehicle care161If w illuminates, stop as soon as
possible and inflate the tyres as
recommended 3 190.
After inflating, driving may be
required to update the tyre pressure
values in the system. During this time
w may illuminate.
If w illuminates at lower temperatures
and extinguishes after some driving,
this could be an indicator for
approaching a low tyre pressure
condition. Check tyre pressure of all
four tyres.
If the tyre pressure must be reduced
or increased, switch off ignition.
Only mount wheels with pressure
sensors, otherwise the tyre pressure
value cannot be recognised by the
system and w flashes for several
seconds then illuminates
continuously. In vehicles with
Multifunction version of the Driver
Information Centre, a corresponding message is also displayed.
A spare wheel or temporary spare
wheel is not equipped with pressure
sensors. The tyre pressure
monitoring system is not operationalfor these wheels. For the further three
wheels, tyre pressure monitoring
system remains operational.
Spare wheel 3 167, Wheel changing
3 165.
Control indicator w and (depending
on version) a corresponding message appears at each ignition cycle until
the tyres are inflated to the correct
tyre pressure.
Driver Information Centre 3 89.
Relearn function
After changing wheels, the tyre
pressure monitoring system needs to recalculate. The relearn process
takes up to 20 minutes of driving with
a minimum speed of 12 mph.
If problems occur during the relearn
process, control indicator w flashes
for several seconds then illuminates
continuously and (depending on
version) a warning message is
displayed in the Driver Information
Centre.
Driver Information Centre 3 89.General information
The use of tyre chains or
commercially available liquid tyre
repair kits can impair the function of
the system. Factory-approved tyre
repair kits can be used.
Tyre repair kit 3 163, Tyre chains
3 162.
Operating electronic devices or being close to facilities using similar wave
frequencies could disrupt the tyre
pressure monitoring system.
Each time the tyres are replaced, tyre
pressure monitoring system sensors
must be dismounted and serviced by
a workshop.
Tread depthCheck tread depth at regular
intervals.
Tyres should be replaced for safety
reasons at a tread depth of 2-3 mm (4 mm for winter tyres).
For safety reasons, it is
recommended that the tread depth of
the tyres on one axle should not vary
by more than 2 mm.
