Maximum load on one tire
Maximum load on one tire. This is calculated
by dividing the maximum axle load of one axleby 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.
Tire pressure of cold tires
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.
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, a roof rack or a high-
performance battery, are not included in the
curb weight and the weight of the accesso-
ries.
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 identifythe 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.
Traction
Traction is the result of friction between the
tires and the road surface.
TWR (Tongue Weight Rating)
The TWR specifies the maximum permissible
weight that the ball coupling of the trailer tow
hitch can support.
354Definition of terms for tires and loading
Wheels and tires
Mounting a wheel
Preparing the vehicle
XStop the vehicle on solid, non-slippery and
level ground.
X Apply the parking brake.
X Bring the front wheels into the straight-
ahead position.
X Move the selector lever to position P.
X Switch off the engine.
X Vehicles without KEYLESS-GO: remove
the SmartKey from the ignition lock.
X Vehicles with KEYLESS-GO: open the
driver's door.
The on-board electronics have status 0,
which is the same as the SmartKey having
been removed.
X Vehicles with KEYLESS-GO: remove the
Start/Stop button from the ignition lock
( Y page 149).
X If a trailer is coupled to the vehicle, uncou-
ple it.
X If included in the vehicle equipment,
remove the tire-change tool kit from the
vehicle.
X In addition, safeguard 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
( Y page 314).
The folding wheel chock is an additional
safety measure to prevent the vehicle from
rolling away, for example when changing a
wheel.
X Fold both plates upwards :.
X Fold out lower plate ;.
X Guide the lugs on the lower plate fully into
the openings in base plate =.
Securing the vehicle on level ground
X
On level ground: place chocks or other
suitable items under the front and rear of
the wheel that is diagonally opposite the
wheel you wish to change.
Securing the vehicle on slight downhill gradients
X On light downhill gradients: place
chocks or other suitable items in front of
the wheels of the front and rear axle.
356Mounting a wheel
Wheels and tires
