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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 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:
Rif the vehicle has been parked with the tires
out of direct sunlight for at least three hours
and
Rif 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.
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 fromthe 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 5 lbs (2.3 kg). These
optional extras, such as high-performance
brakes, level control, a roof rack or a high-per-
formance 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 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 a code
that contains the maximum load bearing capa-
city of a tire.
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 áin (1.6 mm)
has been reached.
Occupant distribution
The distribution of occupants in a vehicle at their
designated seating positions.
Total load limit
Nominal load and luggage load plus 68 kg
(150 lbs) multiplied by the number of seats in
the vehicle.
Changing a wheel
Flat tire
The "Breakdown assistance" section
(Ypage 343) contains information and notes on
how to deal with a flat tire. Information on driv-
ing with MOExtended tires in the event of a flat
tire can be found under "MOExtended tires (tires
with run-flat characteristics" (
Ypage 343).
Rotating the wheels
GWARNING
Interchanging the front and rear wheels may
severely impair the driving characteristics if
the wheels or tires have different dimensions. The wheel brakes or suspension components
may also be damaged. There is a risk of acci-
dent.
Rotate front and rear wheels only if the wheels and tires are of the same dimensions.
!On vehicles equipped with a tire pressure
monitor, electronic components are located
in the wheel.
Changing a wheel379
Wheels and tires
Z
Page 382 of 398

Tire-mounting tools should not be used near
the valve. This could damage the electronic
components.
Only have tires changed at a qualified spe-
cialist workshop.
Always observe the instructions and safety
notes in the "Mounting a wheel" section
(
Ypage 380).
The wear patterns on the front and rear tires
differ, depending on the operating conditions.
Rotate the wheels before a clear wear pattern
has formed on the tires. Front tires typically
wear more on the shoulders and the rear tires in the center.
On vehicles that have the same size front and
rear wheels, you can rotate the wheels accord-
ing to the intervals in the tire manufacturer's
warranty book in your vehicle documents. If no
warranty book is available, the tires should be
rotated every 3,000 to 6,000 miles (5,000 to
10,000 km). Earlier may be necessary, depend-
ing on the degree of tire wear. Do not change the
direction of wheel rotation.
Clean the contact surfaces of the wheel and the
brake disc thoroughly every time a wheel is rota- ted. Check the tire pressure and, if necessary,
restart the tire pressure loss warning system
(
Ypage 367) or the tire pressure monitor
(Ypage 369).
Direction of rotation
Tires with a specified direction of rotation have
additional benefits, e.g. if there is a risk of hydro-
planing. These advantages can only be gained if
the tires are installed corresponding to the
direction of rotation.
An arrow on the sidewall of the tire indicates its
correct direction of rotation.
Storing wheels
Store wheels that are not being used in a cool,
dry and preferably dark place. Protect the tires
from oil, grease, gasoline and diesel.
Mounting a wheel
Preparing the vehicle
XStop the vehicle on solid, non-slippery and
level ground.
XApply the electric parking brake manually.
XBring the front wheels into the straight-ahead position.
XShift the transmission to position P.
XMake sure that the vehicle level is set to "Nor-
mal" on vehicles with AIRMATIC (Ypage 196).
XSwitch off the engine.
XVehicles without KEYLESS-GO:remove the
SmartKey from the ignition lock.
XVehicles with KEYLESS-GO start-function
or KEYLESS-GO: open the driver's door.
The on-board electronics now have status 0.
This is the same as the SmartKey having been
removed.
XVehicles with KEYLESS-GO start-function
or KEYLESS-GO: remove the Start/Stop but-
ton from the ignition lock (
Ypage 146).
XMake sure that the engine cannot be started
via your smartphone (Ypage 149).
XIf included in the vehicle equipment, remove
the tire-change tool kit from the vehicle.
XSafeguard the vehicle against rolling away.
Securing the vehicle to prevent it from
rolling away
If your vehicle is equipped with a wheel chock, it can be found in the tire-change tool kit
(
Ypage 343).
The folding wheel chock is an additional safety
measure to prevent the vehicle from rolling
away, for example when changing a wheel.
380Changing a wheel
Wheels and tires
Page 386 of 398

XClean the wheel and wheel hub contact sur-
faces.
XSlide the wheel to bemounted onto the align-
ment boltand push iton.
XTighten the wheel bolts unt ilthey are finger-
tight.
XUnscrew the alignment bolt.
XTighten the last wheel boltuntil it is finger-
tight.
Lowering the vehicle
GWAR NING
The wheels could work loose ifthe wheel nuts
and bolts are not tightened to the specifie d
tightening torque. There isa risk of acc ident.
Have the tightening torque immediately
checked at a qualified specialist workshop
after a wheel ischanged.
XTurn the crank of the jack counter-clock wise
unt ilthe veh icle isonce again standing firmly
on the ground.
XPlace the jack to one side.
XTighten the wheel bolts evenly ina crosswise
pattern inthe sequence indicated (: toA). The specified tightening torque is
96lb-ft
(1 30 Nm) .
XTurn the jack back to its initial position.
XStow the jack and the rest of the vehicle tools
in the trunk again.
XMercedes-AMG vehicles and vehicles
with AMG equipment: insert the cover into
the outer sill.
XCheck the tire pressure of the ne wlymounted
wheel and adjust it if necessary.
Observe the recommended tire pressure
(
Ypage 363).
When you are driving with the collapsible spare
wheel mounte d,the tire pressure loss warning
system or the tire pressure monitor cannot func-
tion reliably. Only restart the tire pressure loss
warning system or tire pressure monitor when
the defective wheel has been replaced with a
new wheel.
Vehicles with a tire pressure controlsys-
tem: all installed wheels must be equipped with
functioning sensors.
Wheel-tire combination
You can ask for information regarding permitted
wheel-tire co mbinations at an authorized
Mercedes-Benz Center.
!For safety reasons, Mercedes-Benz recom-
men dsthat you only use tires and wheels
whic h have been approved by Mercedes-Benz
specifically for your vehicle.
These tires have been specially adapted for
use with the control systems, such as ABS or
ESP
®, and are marked as follows:
RMO = Mercedes-Benz Original
RMOE = Mercedes-Benz Original Extended
(tires featuring run-flat characteristics)
RMO1 = Mercedes-Benz Original (only cer-
tain AMG tires)
Mercedes-Benz Original Extended tires may
only be used on wheels that have been spe-
cifically approved by Mercedes-Benz.
Only use tires, wheels or accessories tested
and approved by Mercedes-Benz. Certain
characteristics, e.g. handling, vehicle noise
emissions or fuel consumption, may other-
wise be adverselyaffected. In addition, when
driv ingwith a load, tire dimension variations
could cause the tires to come into contact
384Wheel-tire combination
Wheels and tires