
malfunction indicator is combined with the
low tire pressure telltale. When the system
detects a malfunction, the warning lamp will
flash for approximately a minute and then
remain continuously illuminated. This
sequence will be repeated every time the
vehicle is started as long as the malfunction
exists.
When
the malfunction indicator is illuminated,
the system may not be able to detect or signal
low tire pressure as intended. TPMS
malfunctions may occur for a variety of
reasons, including the installation of
incompatible replacement or alternate tires
or wheels on the vehicle that prevent the
TPMS from functioning properly. Always
check the TPMS malfunction telltale after
replacing one or more tires or wheels on your
vehicle to ensure that the replacement or
alternate tires and wheels allow the TPMS to
continue to function properly.
It is the driver's responsibility to set the tire
pressure to the recommended cold tire
pressure suitable for the operating situation
(Y page 322). Note that the correct tire
pressure for the current operating situation
must first be taught-in to the tire pressure
monitor. If there is a substantial loss of
pressure, the warning threshold for the
warning message is aligned to the reference
values taught-in. Restart the tire pressure
monitor after adjusting to the cold tire
pressure ( Y page 327). The current
pressures are saved as new reference values.
As a result, a warning message will appear if
the tire pressure drops significantly.
The tire pressure monitor does not warn you
of an incorrectly set tire pressure. Observe
the notes on the recommended tire pressure
(Y page 322).
The tire pressure monitor is not able to warn
you of a sudden loss of pressure, e.g. if the
tire is penetrated by a foreign object. In the
event of a sudden loss of pressure, bring the
vehicle to a halt by braking carefully. Avoid
abrupt steering maneuvers. If a tire pressure monitor system is installed,
the vehicle's wheels have sensors installed
that
monitor the tire pressures in all four tires.
The tire pressure monitor warns you if the
pressure drops in one or more of the tires. The
tire pressure monitor only functions if the
correct wheel electronics units are installed
on each wheel.
The tire pressure monitor has a yellow
warning lamp in the instrument cluster for
indicating pressure loss/malfunctions (USA)
or pressure loss (Canada). Whether the
warning lamp flashes or lights up indicates
whether a tire 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 malfunctioning.
R USA only: if the warning lamp flashes for
around a minute and then remains lit
constantly, the tire pressure monitor is
malfunctioning.
Information on tire pressures is displayed in
the multifunction display. After a few minutes
of driving, the current tire pressure of each
tire is shown in the multifunction display.
USA only: if there is a malfunction with the
tire pressure monitor it can take more than
ten minutes until the malfunction is shown by
the tire pressure warning lamp flashing for
approximately one minute and then lighting
up continuously. When the malfunction has
been rectified, the tire pressure warning lamp
goes out after a few minutes of driving.
The tire pressure values indicated by the on-
board computer may differ from those
measured at a gas station with a pressure
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. 326
Tire pressure
Wheels and tires

The operation of the tire pressure monitor can
be affected by interference from radio
transmitting equipment (e.g. radio
headphones, two-way radios) that may be
being operated in or near the vehicle.
i
USA only:
This device complies with part
15 of the
FCC Rules. Operation is subject to the
following two conditions:
1. This device may not cause interference,
and
2. this device must accept any interference
received, including interference that may
cause undesired operation of the device.
Any unauthorized modification to this
device could void the user's authority to
operate the equipment.
i Canada only:
This device complies with RSS-210 of
Industry Canada. Operation is subject to
the following two conditions:
1. This device may not cause interference,
and
2. this device must accept any interference
received, including interference that may
cause undesired operation.
Any unauthorized modification to this
device could void the user's authority to
operate the equipment.
Checking tire pressure electronically X
Make sure that the SmartKey is in
position 2 (Y
page 139) in the ignition lock.
X Press the = or ; button on the
steering wheel to select the Serv. menu.
X Press the 9 or : button to select
Tire Pressure.
X Press button a.
The
current tire pressure for each wheel will
be displayed in the multifunction display.
If the vehicle has been parked for over
20 minutes, the message Tire pressure will be displayed after driving a
few minutes appears.
After a teach-in period, the tire pressure
monitor
automatically recognizes new wheels
or new sensors. As long as a clear allocation
of the tire pressure values to the individual
wheels is not possible, the Tire Pressure
Monitor Active display message is shown
instead of the tire pressure display. The tire
pressures are already being monitored.
i If a spare wheel is mounted, the system
may continue to show the tire pressure of
the wheel that has been removed for a few
minutes. If this occurs, note that the value
displayed for the position where the spare
wheel is mounted is not the same as the
spare wheel's current tire pressure.
Tire pressure monitor warning
messages If the tire pressure monitor detects a
significant
pressure loss on one or more tires,
a warning message is shown in the
multifunction display. A warning tone also
sounds and the tire pressure warning lamp
lights up in the instrument cluster.
Each tire that is affected by a significant loss
of pressure is highlighted in the pressure
display.
X If the Correct Tire PressureCorrect
Tire Pressure message appears in the
multifunction display, check the tire
pressure
on all four wheels and correct it if
necessary.
i If the wheel positions on the vehicle are
interchanged, the tire pressures may be
displayed for the wrong positions for a
short time. This is rectified after a few
minutes of driving, and the tire pressures
are displayed for the correct positions.
Restarting the tire pressure monitor When you restart the tire pressure monitor,
all
existing warning messages are deleted and
the warning lamps go out. The monitor uses Tire pressure
327
Wheels and tires Z

the currently set tire pressures as the
reference values for monitoring. In most
cases, the tire pressure monitor will
automatically detect the new reference
values after you have changed the tire
pressure. However, you can also define
reference
values manually as described here.
X Set the tire pressure to the value
recommended for the corresponding
driving situation on the Tire and Loading
Information placard on the driver's side
B-pillar ( Y page 322).
Additional
tire pressure values for different
loads can also be found on the tire pressure
table on the inside of the fuel filler flap
(Y page 322).
X Make sure that the tire pressure is correct
on all four wheels.
X Make sure that the SmartKey is in
position 2 (Y
page 139) in the ignition lock.
X Press the = or ; button on the
steering wheel to select the Serv. menu.
X Press the 9 or : button to select
Tire Pressure.
X Press the a button.
The multifunction display shows the
current
tire pressure for the individual tires
or the Tire pressure will be
displayed after driving a few
minutes message.
X Press the : button.
The Use Current Pressures as New
Reference Values message appears in
the multifunction display.
If you wish to confirm the restart:
X Press the a button.
The Tire Press. Monitor Restarted
message appears in the multifunction
display.
After
driving for a few minutes, the system
checks whether the current tire pressures
are within the specified range. The new tire
pressures are then accepted as reference
values and monitored. If you wish to cancel the restart:
X
Press the % button.
The tire pressure values stored at the last
restart will continue to be monitored. Loading the vehicle
Instruction labels for tires and loads
G
WARNING
Overloaded tires can overheat, causing a
blowout.
Overloaded tires can also impair the
steering and driving characteristics and lead
to brake failure. There is a risk of accident.
Observe the load rating of the tires. The load
rating must be at least half of the GAWR of
your vehicle. Never overload the tires by
exceeding the maximum load. :
B-pillar, driver's side
Two instruction labels on your vehicle show
the maximum possible load.
(1) The Tire and Loading Information placard is
on the B-pillar on the driver's side. The
Tire and Loading Information placard
shows the maximum permissible number
of occupants and the maximum
permissible vehicle load. It also contains
details of the tire sizes and
corresponding pressures for tires
mounted at the factory.
(2) The vehicle identification plate is on the B-pillar on the driver's side. The vehicle
identification plate informs you of the
gross
vehicle weight rating. It is made up328
Loading the vehicle
Wheels and tires

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 Vehicle
Safety Standard No. 109. Grades B and A
represent higher levels of performance on the
laboratory test wheel than the minimum
required by law. Tire labeling
Tire labeling overview
:
Uniform tire Quality Grading Standard
(Y page 338)
; DOT tire Identification Number
(Y page 337)
= Maximum tire load ( Y page 337)
? Maximum tire pressures (Y page 324)
A Manufacturer
B Tire material ( Y page 337)
C Tire size designation, load-bearing
capacity and speed rating
(Y page 334)
D Load identification ( Y page 336)
E Tire name
The markings described above are on the tire
in addition to the tire name (sales
designation) and the manufacturer's name. i
Tire data is vehicle-specific and may
deviate from the data in the example. Tire size designation, load-bearing
capacity and speed rating
G
WARNING
Exceeding the stated tire load-bearing
capacity and the approved maximum speed
could
lead to tire damage or the tire bursting.
There is a risk of accident.
Therefore, only use tire types and sizes
approved for your vehicle model. Observe the
tire load rating and speed rating required for
your vehicle. :
Tire width
; Height-width ratio in percentage
= Tire code
? Rim diameter
A Load bearing index
B Speed rating
General: depending on the manufacturer's
standards, a letter is imprinted into the tire
wall before the size description.
If there is no letter preceding the size
description (as shown above): these are
passenger vehicle tires according to
European manufacturing standards.
If "P" precedes the size description:
passenger vehicle tires according to U.S.
manufacturing standards. 334
Tire labeling
Wheels and tires

If "P" precedes the size description: light
truck tires according to U.S. manufacturing
standards.
If
"T" precedes the size description: these are
compact emergency spare wheels at high tire
pressure, to be used only temporarily in an
emergency.
Tire width: tire width : shows the nominal
tire width in millimeters.
Height-width ratio: height-width ratio ; is
the ratio between tire height and tire width.
The aspect ratio is calculated by dividing the
tire width by the tire height. The resulting
quotient is given as a percentage.
Tire code: tire code = shows the tire type.
"R" represents radial tires; "D" represents
diagonal tires; "B" represents diagonal radial
tires.
Optionally, tires with a maximum speed of
over 149 mph (240 km/h) may have "ZR" in
the size description, depending on the
manufacturer (e.g. 245/40 ZR 18).
Rim diameter: rim diameter ? is the
diameter of the bead seat, not the diameter
of the rim flange. The rim diameter is
specified in inches (in).
Load bearing index: B load bearing index
A (also load index) is a numerical code that
specifies the maximum load-bearing capacity
of a tire.
Do not overload the tires by exceeding the
specified load limit. The maximum
permissible load can be found on the
vehicle's Tire and Loading Information
placard on the B-pillar on the driver's side
(Y page 328).
Example:
Load-bearing index 91 indicates a maximum
load of 1356 lbs (615 kg) that the tires can
bear. For further information on the maximum
tire load in kilograms and pounds, see
(Y page 337).
For further information on the load bearing
index, see "Load index" ( Y page 336).Speed rating:
speed rating B specifies the
approved maximum speed of the tire.
i Tire data is vehicle-specific and may
deviate from the data in the example.
Regardless of the speed rating, always
observe the speed limits. Drive carefully and
adapt your driving style to the traffic
conditions.
i Since 2009, tires in Europe which
correspond to the noise limitations of
Directive ECE-R 117 show an >>S<<
(Sound) mark. This identification follows
the type approval number and has no
connection with the speed rating.
Summer tires Index Speed rating
Q up to 100 mph (160 km/h)
R up to 106 mph (170 km/h)
S up to 112 mph (180 km/h)
T up to 118 mph (190 km/h)
H up to 130 mph (210 km/h)
V up to 149 mph (240 km/h)
W up to 168 mph (270 km/h)
Y up to 186 mph (300 km/h)
ZR...Y up to 186 mph (300 km/h)
ZR...(..Y) over 186 mph (300 km/h)
ZR over 149 mph (240 km/h)
R
Optionally, tires with a maximum speed of
over 149 mph (240 km/h
) may have "ZR"
in the size description, depending on the
manufacturer (e.g. 245/40 ZR18).
The service specification is made up of
load-bearing index A and speed rating
B.
R If the size description of your tire includes
"ZR" and there are no service Tire labeling
335
Wheels and tires Z

specifications, ask the tire manufacturer in
order to find out the maximum speed.
If a service specification is available, the
maximum
speed is limited according to the
speed rating in the service specification.
Example: 245/40 ZR 18 97 Y. In this
example, "97 Y" is the service specification.
The letter "Y" represents the speed rating
and the maximum speed of the tire is
limited to 186 mph(300 km/h).
R The size description for all tires with
maximum speeds of over 186 mph
(300 km/h) must include "ZR" and the
service specification must be given in
parentheses. Example:
275/40 ZR 18 (99 Y). The speed rating "(Y)"
indicates that the maximum speed of the
tire is over 186 mph (300 km/h). Ask the
tire manufacturer about the maximum
speed.
All-weather tires and winter tires Index Speed rating
Q M+S
4 up to 100 mph (160 km/h)
T M+S
4 up to 118 mph (190 km/h)
H M+S
4 up to 130 mph (210 km/h)
V M+S
4 up to 149 mph (240 km/h)
i
Not
all tires with the M+S marking provide
the driving characteristics of winter tires.
In addition to the M+S marking, winter tires
also have the i snowflake symbol on
the tire wall. Tires with this marking fulfill
the requirements of the Rubber
Manufacturers Association (RMA) and the
Rubber Association of Canada (RAC).
These tires have been developed
specifically for driving on snow.
When the electronic speed limiter is set, your
vehicle is prevented from exceeding 130 mph
(210 km/h). The speed rating of tires mounted at the
factory may be higher than the maximum
speed that the electronic speed limiter
permits.
Make sure that your tires have the required
speed
rating, e.g. when buying new tires. The
required speed rating for your vehicle can be
found in the "Tires" section ( Y page 346).
Further information about reading tire data
can be obtained from any qualified specialist
workshop. Load index
In addition to the load bearing index, load
rating : may be imprinted after the letters
that identify speed rating B on the sidewall
of the tire (Y page 334).
R
If
no specification is given: no text (as in the
example above), represents a standard
load (SL) tire
R XL or Extra Load: represents a reinforced
tire
R Light Load: represents a light load tire
R C, D, E: represents a load range that
depends on the maximum load that the tire
can carry at a certain pressure
i Tire data is vehicle-specific and may
deviate from the data in the example.
4 Or M+S i for winter tires.336
Tire labeling
Wheels and tires

This information describes the type of tire
cord and the number of layers in
sidewall
: and under tire tread ;.
i Tire data is vehicle-specific and may
deviate from the data in the example. Definition of terms for tires and
loading
Tire ply composition and material used Describes the number of layers or the number
of rubber-coated belts in the tread and the
sidewall of the tire. These are made of steel,
nylon, polyester and other materials.
Bar
Metric unit for tire pressure.
14.5038 pounds
per square inch (psi) and
100 kilopascals (kPa) are the equivalent of
1 bar.
DOT (Department of Transportation) DOT marked tires fulfill the requirements of
the United States Department of
Transportation.
Normal occupant weight
The number of occupants for which the
vehicle is designed multiplied by
68 kilograms (150 lbs).
Uniform
Tire Quality Grading StandardsA uniform standard to grade the quality of
tires
with regards to tread quality, tire traction
and temperature characteristics. Ratings are
determined by tire manufacturers using U.S.
government testing procedures. The ratings
are molded into the sidewall of the tire.
Recommended tire pressure The recommended tire pressure applies to
the tires mounted at the factory. The Tire and Loading Information placard
contains
the recommended tire pressures for
cold tires on a fully loaded vehicle and for the
maximum permissible vehicle speed.
The tire pressure table contains the
recommended pressures for cold tires for
various operating conditions, i.e. differing
load and speed conditions.
Increased vehicle weight due to
optional equipment This is the combined weight of all standard
and optional equipment available for the
vehicle, regardless of whether it is actually
installed on the vehicle or not.
Rim
This is the part of the wheel on which the tire
is mounted.
GAWR (Gross Axle Weight Rating)
The GAWR is the maximum gross axle weight
rating.
The actual load on an axle must never
exceed the gross axle weight rating. The
gross axle weight rating can be found on the
vehicle identification plate on the B-pillar on
the driver's side.
Speed rating The speed rating is part of the tire
identification.
It specifies the speed range for
which the tire is approved.
GTW (Gross Trailer Weight) The GTW is the weight of a trailer including
the weight of the load, luggage, accessories
etc. on the trailer.
GVW (Gross Vehicle Weight)
The gross vehicle weight includes the weight
of the vehicle including fuel, tools, the spare
wheel, accessories installed, occupants,
luggage and the drawbar noseweight, if
applicable.
The gross vehicle weight must not338
Tire labeling
Wheels and tires

exceed the gross vehicle weight rating GVWR
as
specified on the vehicle identification plate
on the B-pillar on the driver's side.
GVWR (Gross Vehicle Weight Rating) The GVWR is the maximum permissible gross
weight
of a fully loaded vehicle (the weight of
the vehicle including all accessories,
occupants, fuel, luggage and the drawbar
noseweight, if applicable). The gross vehicle
weight rating is specified on the vehicle
identification plate on the B-pillar on the
driver's side.
Maximum loaded vehicle weight The maximum weight is the sum of:
R
the curb weight of the vehicle
R the weight of the accessories
R the load limit
R the weight of the factory installed optional
equipment
Kilopascal (kPa) Metric unit for tire pressure. 6.9 kPa
corresponds to 1 psi. Another unit for tire
pressure
is bar. 100 kilopascals (kPa) are the
equivalent of 1 bar.
Load index In addition to the load-bearing index, the load
index may also be imprinted on the sidewall
of the tire. This specifies the load-bearing
capacity more precisely.
Curb weight
The weight of a vehicle with standard
equipment including the maximum capacity
of
fuel, oil and coolant. It also includes the air-
conditioning system and optional equipment
if these are installed in the vehicle, but does
not include passengers or luggage. Maximum load rating The maximum tire load is the maximum
permissible weight in kilograms or lbs for
which a tire is approved.
Maximum permissible tire pressure
Maximum permissible tire pressure for one
tire.
Maximum load on one tire
Maximum load on one tire. This is calculated
by
dividing the maximum axle load of one axle
by two.
PSI (pounds per square inch) A standard 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
outward
force to each square inch of the tire's
surface. 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 without
direct
sunlight on the tires for at least three
hours and
R if the vehicle has not been driven further
than 1 mile (1.6 km)
Tread The part of the tire that comes into contact
with the road. Tire labeling
339
Wheels and tires Z