Aspect ratio: relationship between tire height
and tire width in percent.
Tire pressure: pressure inside the tire applying
an outward force to every 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 correc‐
ted when the tires are cold.
Tire pressure on cold tires: the tires are cold
when the vehicle has been parked with the tires
out of direct sunlight for at least three hours and
the vehicle has been driven less than 1 mile
(1.6 km).
Tire contact surface: the part of the tire that
comes into contact with the road.
Tire bead: the purpose of the tire bead is to
ensure that the tire sits securely on the wheel
rim. There are several wire cores in the tire bead
to prevent the tire from changing length on the
wheel rim.
Side wall: the part of the tire between the tread
and the tire bead.
Special equipment weight: 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 system, a
roof luggage rack or a high-performance battery,
are not included in the curb weight and the
weight of the accessories.
TIN (Tire Identification Number): a unique iden‐
tification number 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 identifi‐
cation code, tire size, tire type code and the man‐
ufacturing 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.
Wear indicator: narrow bars (tread wear bars)
that are distributed over the tire tread. If the tire
tread is level with the bars, the wear limit of
1/16 in (1.6 mm) has been reached.
Distribution of vehicle occupants: distribution
of vehicle occupants over designated seat posi‐
tions in a vehicle.
Maximum permissible payload weight: nomi‐
nal load and luggage load plus 150 lbs (68 kg)
multiplied by the number of seats in the vehicle.
Changing a wheel
Notes on selecting, installing and replacing
tires
You can ask for information regarding permitted
wheel/tire combinations at a qualified specialist
workshop.
&
WARNING Risk of accident due to incor‐
rect sizes of wheels and tires
If wheels and tires of the wrong size are used,
the wheel brakes or wheel suspension com‐
ponents may be damaged.
#
Always replace wheels and tires with
ones that fulfill the specifications of the
original part.
For wheels, pay attention to the following:
R
Designation
R
Type
R
Permissible wheel load
R
Wheel offset
For tires, pay attention to the following:
R
Designation
R
Manufacturer
R
Type
R
Load-bearing index
R
Speed rating
&
WARNING Risk of injury through exceed‐
ing the specified tire load rating or the
permissible speed rating
Exceeding the specified tire load rating or the
permissible speed rating may lead to tire
damage and to the tires bursting.
#
Therefore, only use tire types and sizes
approved for your vehicle model.
#
Observe the tire load rating and speed
rating required for your vehicle.
Wheels and tires 257
