The tire pressure monitor has ay ellow warning
lamp in the instrument cluster for indicating
pressure loss or am alfunction. Whether the
warning lamp flashes or lights up indicates
whether at ire pressure is too low or the tire
pressure monitor is malfunctioning: R
if the warning lamp is lit continuously, the tire
pressure on one or more tires is significantly
too low. The tire pressure monitor is not mal-
functioning. R
if the warning lamp flashes for around a
minute and then remains lit constantly, the
tire pressure monitor is malfunctioning.
In addition to the warning lamp, am essage
appears in the multifunction display .O bserve
the information on display messages
( Y
page 211).
It may take up to ten minutes for am alfunction
of the tire pressure monitor to be indicated. A
malfunction will be indicated by the tire pres-
sure warning lamp flashing for approximately
one minute and then remaining lit. When the
malfunction has been rectified, the tire pressure
warning lamp goes out after af ew minutes of
driving.
The tire pressure values indicated by the on-
board computer may differ from those meas-
ured at ag as station with ap ressure gauge. The
tire pressures shown by the on-board computer
refer to those measured at sea level. At high
altitudes, the tire pressure values indicated by a
pressure gauge are higher than those shown by
the on-board computer. In this case, do not
reduce the tire pressures.
The operation of the tire pressure monitor can
be affected by interferenc ef rom radio transmit-
ting equipment (e.g. radio headphones, two-way
radios) that may be being operated in or near the
vehicle.
Checking the tire pressur ee lectroni-
cally X
Make sure that the SmartKey is in position H
in the ignition lock ( Y
page 122).X
Press Y or e on the steerin gw heel to
select the Serv. menu.X
Press the c or d button to select
Tire Pressure .X
Press the v button.
The current tire pressure of each tire is shown
in the multifunction display. If the vehicle was parked for longer than
20 minutes, the Tire pressure will be
displayed after driving af ew minutes
message is shown.
After at each-in process, the tire pressure mon-
itor automatically detect sn ew wheels or new
sensors. As long as ac lear allocation of the tire
pressure value to the individual wheels is not
possible, the Tire Pressure Monitor Active
message is shown instead of the tire pressure
display .T he tire pressures are already being
monitored.
If an emergenc ys pare wheel is mounted, the
system may continue to show the tire pressure
of the wheel that has been removed for af ew
minutes. If this occurs, not et hat the value dis-
played for the position where the spare wheel is
mounted is not the same as the current tire
pressure of the emergenc ys pare wheel.
Tire pressur em onitor warning mes-
sages If the tire pressure monitor detect sap ressure
loss in one or more tires, aw arning message is
shown in the multifunction display .T he yellow
tire pressure warning lamp then lights up. R
If the Please Correct Tire Pressure
message appears in the multifunction display,
the tire pressure in at least one tire is too low.
The tire pressure must be corrected when the
opportunit ya rises. R
If the Check Tire Pressure message
appears in the multifunction display ,t he tire
pressure in one or more tires has dropped
significantly. The tires must be checked. R
If the Tire Pressure Warning Tire Fail‐
ure message appears, the tire pressure in one
or more tires has dropped suddenly. The tires
must be checked.
Observe the instructions and safety notes in the
display messages in the "Tires" section
( Y
page 211).
If the wheel positions on the vehicle are rotated,
the tire pressures may be displayed for the
wrong positions for as hort time. This is rectified
after af ew minutes of driving, and the tire pres-
sures are displayed for the correc tp ositions.296
Tir ep re ssure
Wheels and tires
PSI (pounds per squar ei nch)As tandard unit of measure for tire pressure.
Aspect ratio Relationship between tire height and tire width
in percent.
Tire pressure This is pressure inside the tire applying an out-
ward force to each square inch of the tire's sur-
face. The tire pressure is specified in pounds per
square inch (psi), in kilopascal (kPa) or in bar.
The tire pressure should only be corrected when
the tires are cold.
Cold tire pressure The tires are cold: R
if the vehicle has been parked with the tires
out of direct sunlight for at least three hours
and R
if the vehicle has not been driven further than
1m ile (1.6 km)
Tread The part of the tire that comes into contact with
the road.
Bead The tire bead ensures that the tire sits securely
on the wheel. There are several steel wires in the
bead to prevent the tire from coming loose from
the wheel rim.
Sidewall The part of the tire between the tread and the
bead.
Weight of optional extras
The combined weight of those optional extras
that weigh more than the replaced standard
parts and more than 2.3 kg (5 lbs). These
optional extras, such as high-performance
brakes, level control, ar oof rack or ah igh-per-
formanc eb attery, are not included in the curb
weight and the weight of the accessories.
TIN (Tire Identification Number)
This is au nique identifier which can be used by
at ire manufacturer to identify tires, for example
for ap roduct recall, and thus identify the pur-
chasers. The TIN is made up of the manufactur-
er's identity code, tire size, tire type code and
the manufacturing date. Load bearing index The load bearing index (also load index) is ac ode
that contains the maximum load bearing capa-
city of at ire.
Traction Traction is the result of friction between the tires
and the road surface.
Treadwear indicators Narrow bars (tread wear bars) that are distrib-
uted over the tire tread. If the tire tread is level
with the bars, the wear limit of
