pressure, to be used only temporarily in an
emergency.
Tire width:
tire width:shows the nominal
tire width in millimeters.
Height-width ratio: aspect ratio;is the
size ratio between the tire height and tire
width and is shown as a percentage. The
aspect ratio is calculated by dividing the tire
width by the tire height.
Tire code: tire code=specifies 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: load-bearing indexA
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 323).
Example:
The load bearing index 91 indicates a
maximum load of 1356 lb (615 kg) that the
tires can bear. For further information on the
maximum tire load in kilograms and pounds,
see (Y page 330).
For further information on the load bearing
index, see "Load index" (Y page 330).
Speed rating: speed ratingBspecifies 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.
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 130mph (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 a “ZR”
in the size description, depending on the
manufacturer (e.g. 245/40 ZR18).
The service specification is made up of
load-bearing index Aand speed rating
B.
R If the size description of your tire includes
"ZR" and there are no service
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 servic especification.
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 (300km/h).
R Every tire that has amaximum speed of
mor ethan 186 mph (300 km/h) must have
a "ZR" in the size description andthe
service specification must be given in All about wheels and tires
329Wheels and tires Z
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 323).
i The actual values for tires are vehicle-
specific and may deviate fro mthe values in
the illustration.
DOT, Tire Identification Number (TIN) U.S. tire regulations prescribe that every tire
manufacturer or retreader must imprint
aTIN
in or on the sidewall of every tire produced. The TIN is a unique identification number. The
TIN enables the tire manufacturers or
retreaders to inform purchasers of recalls and
other safety-relevant matters. It makes it
possible for the purchaser to easily identify
the affected tires.
The TIN is made up of manufacturer
identification code
;, tire size=, tire type
code ?and manufacturing date A.
DOT (Department of Transportation): tire
symbol :indicates that the tire complies
with the requirements of the U.S. Department
of Transportation.
Manufacturer identification code:
manufacturer identification code ;provides
details on the tire manufacturer. New tires
have a code with two symbols. Retreaded
tires have a code with four symbols.
For further information aboutr etreaded tires,
see (Y page 339). Tire size:
identifier=describes the tire size.
Tire type code: tire type code?can be used
by the manufacturer as acode to describe
specific characteristics of the tire.
Date of manufacture: date of manufacture
A provides information about the age of a
tire. The first and second positions represent
the week of manufacture, starting with "01"
for the first calendar week. Positions three
and four represent the year of manufacture.
For example, a tire that is marked with
"3208", was manufactured in week 32 in
2008.
i Tire data is vehicle-specific and may
deviate from the data in the example.
Tire characteristics 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 plies or the number
of layers of rubber-coated fabric in the tire
tread and sidewall. These are made of steel,
nylon, polyester and other materials.
Bar
Metric unit for tire pressure.
14.5038 pounds per square inch (psi) and All about wheels and tires
331Wheels and tires Z
Load index
In addition to the load-bearing index, the load
inde
xmay also be imprinted on the sidewall
of the tire. This specifie sthe 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)
As tandard uni tofmeasure 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 been driven for less than
1 mile (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 kilograms (5 lbs).
These optional extras, such as high-
performance brakes, level control, a roof rack
or a high-performance battery, are not
included in the curb weight and the weight of
the accessories.
TIN (Tire Identification Number)
This is a unique identifier which can be used
by a tire manufacturer to identify tires, for
example for a product recall, and thus identify
the purchasers. The TIN is made up of the
manufacturer's identity code, tire size, tire
type code and the manufacturing date.
Load bearing index
The load bearing index (also load index) is a
code that contains the maximum load bearing
capacity of a tire. All about wheels and tires
333Wheels and tires Z
The recommended pressures for various
operating conditions can be found:
R
on the Tire and Loading Information placard
with the recommended tire pressures on
the B-pillar on the driver's side
R in the tire pressure table on the inside of
the fuel filler flap
Observe the notes on recommended tire
pressures under various operating conditions
(Y page 316).
Check tire pressures regularly, and only when
the tires are cold. Comply with the
maintenance recommendations of the tire
manufacturer in the vehicle document wallet.
Notes on the vehicle equipment –always
equip the vehicle with:
R tires of the same size on a given axle (left/
right)
R the same type of tires at a given time
(summer tires, winter tires, MOExtended
tires)
Vehicles with MOExtended tires are not
equipped with a TIREFIT kit at the factory. It
is therefore recommended that you
additionally equip your vehicle with a TIREFIT
kit if you mountt ires that do not feature run-
flat properties, e.g. winter tires. ATIREFIT kit
may be obtained from a qualified specialist
workshop.
In the following table, the wheel/tire
combinations are assigned to the vehicle
models through variants, e.g. V1, V2 etc.: V1
R 350
18 V2 R 350 BlueTEC
i
Not all wheel and tire combinations are
available at the factory for all countries.
i On the following pages, you can find
information on approved wheelr ims and
tire sizes for equipping your vehicle with
winter tires. Winter tires are not available at the factory as standard equipmen
tor
optional extras.
If you would like to equip your vehicle with
approved winter tires, you may also, in
certain circumstances, require rims of the
appropriate size. The sizes of the approved
winter tires may deviate from that of the
standard tires. This is dependent on the
model and the equipment installed at the
factory.
The tires and wheel rims, as well as further
information, can be obtained at a qualified
specialist workshop.
18 BlueEFFICIENCY 340
Wheel and tire combinationsWheels and tires
R20
Tires Alloyw
heels V1 V2
BA: 265/45 R20 108 H XL
M+Si
20 BA: 9.0 J x 20 H2
Wheel offset: 2.36 in (60 mm) #
—
Emergency spare wheel
Important safety notes
G
WARNING
The wheel or tire size as well as the tire type
of the spare wheel or emergency spare wheel
and the wheel to be replaced may differ.
Mounting an emergency spare wheel may
severely impair the driving characteristics.
There is a risk of an accident.
To avoid hazardous situations:
R adapt yourd riving style accordingly and
drive carefully.
R never install more than one spare wheel or
emergency spare wheel that differs in size.
R only use a spare wheel or emergency spare
wheel of a different size briefly.
R do not switch ESP ®
off.
R have a spare wheel or emergency spare
wheel of a different size replaced at the
nearest qualified specialist workshop.
Observe that the wheel and tire dimensions
as well as the tire type must be correct.
When using an emergency spare wheel or
spare wheel of a different size, you must not
exceed the maximum speed of 50 mph
(80 km/h).
Snow chains must not be mounted on
emergency spare wheels. General notes
Mounting the emergency spare wheel is
described under "Mounting a wheel"
(Y page 335). An emergency spare wheel may also be
mounted against the direction of rotation.
Observe the time restriction on use as well as
the speed limitation specified on the
emergency spare wheel.
Replace the tires after six years at the latest,
regardless of wear. This also applies to the
emergency spare wheel.
Removing the emergency spare wheel
The collapsible spare wheel can be found in
the stowage well under the cargo
compartment floor.
X
Lift the cargo compartment floor up
(Y page 298).
X Remove the jack from the tool holder.
X Turn retaining screw :counter-clockwise
and out of tool holder =and remove it.
i If retaining screw :does not come out
immediately, turn tool holder =slightly
counter-clockwise.
Retaining screw :can then be unscrewed
with ease.
20 Use of snow chains not permitted. Observe the notes under "Snow chains". 342
Emergency spare wheelWheels and tires