Page 179 of 233

Vehicle care177Rear-wheel drive, with twin rear
wheels
When inflating the outer tyre, the
inflation tube should be passed
between the two wheels.
Tyre pressure monitoring system
The Tyre Pressure Monitoring
System (TPMS) 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.
All wheels must be equipped with pressure sensors and the tyres must
have the prescribed pressure.
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.
The TPMS sensors monitor the air
pressure in the tyres and transmit tyre pressure readings to a receiver
located in the vehicle.
Tyre pressure chart 3 219.
Tyre pressures in display
The current tyre pressures can be
shown in the Driver Information
Centre (DIC) 3 89.With the vehicle stationary, press
button on end of wiper lever
repeatedly until the tyre pressure
menu is displayed.
Low tyre pressure condition
A detected low tyre pressure
condition is indicated by illumination
of control indicator w 3 87 and a
corresponding message appears in
the DIC.
If w illuminates, stop as soon as
possible and inflate the tyres as
recommended 3 219.
Page 180 of 233

178Vehicle careAfter inflating, some driving may be
required to update the tyre pressure
values in the DIC. 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
will not be displayed and w flashes for
several seconds then illuminates
continuously together with control
indicator A 3 85 and a
corresponding message appears in
the DIC.
A spare wheel or temporary spare
wheel is not equipped with pressure
sensors. TPMS is not operational for
these wheels. For the further three
wheels, TPMS remains operational.Control indicator w and the
corresponding message appears at
each ignition cycle until the tyres are
inflated to the correct tyre pressure.
Driver Information Centre (DIC) 3 89.
Vehicle messages 3 90.
Puncture A puncture or severely under-inflated
tyre is indicated by illumination of
control indicator w together with C
3 85 and a corresponding message
appears in the DIC. Stop vehicle and
switch off engine.
Tyre pressure 3 219, Tyre repair kit
3 180, Spare wheel 3 185, Wheel
changing 3 184.
Temperature dependency 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 a10 °C temperature increase. This
must be considered when warm tyres
are checked.
The tyre pressure value displayed in
the DIC shows the actual tyre
pressure. A cooled down tyre will show a decreased value, which does
not indicate an air leak.
Relearn function
After changing the wheels, TPMS
needs to recalculate.
With the vehicle stationary, select the tyre pressure menu in the DIC by
pressing button on end of wiper lever. Press and hold button for approx.
Page 181 of 233

Vehicle care1795 seconds to initialise recalculation. A
corresponding message appears in
the DIC.
Several minutes of driving at a speed
above 25 mph may be required to
complete the relearn process. The
system can only provide limited
information during this time.
If problems occur during the relearn
process, control indicator w remains
illuminated and a warning message is displayed in the DIC.
Driver Information Centre (DIC) 3 89.
Vehicle messages 3 90.
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 3 180, Tyre chains
3 180.
External high-power radio equipment
could disrupt the TPMS.
Each time the tyres are replaced,
TPMS sensors must be dismounted
and serviced by a workshop.Tread depth
Check 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.
The legally permissible minimum
tread depth (1.6 mm) has been
reached when the tread has worn
down as far as one of the tread wear
indicators (TWI). Their position is
indicated by markings on the
sidewall.
Tyres age, even if they are not used.
We recommend tyre replacement
every 6 years.
Changing tyre and wheel size
If tyres of a different size than those fitted at the factory are used, it may be necessary to reprogramme the
speedometer as well as the nominal
tyre pressure and make other vehicle modifications.
After converting to a different tyre
size, have the label with tyre
pressures replaced.9 Warning
Use of unsuitable tyres or wheels
may lead to accidents and will
invalidate the vehicle type
approval.