these are installed on the vehicle, but does not
include passengers or luggage.
Maximum tire load: the maximum tire load is
the maximum permissible weight in kilograms or
lbs for which a tire is approved.
Maximum permissible tire pressure: maxi‐
mum permissible tire pressure for one tire.
Maximum load on one tire: maximum load on
one tire. This is calculated by dividing the maxi‐
mum axle load of one axle by two.
PSI (pounds per square inch): standard unit of
measurement for tire pressure.
Aspect ratio: ratio 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.
The tire pressure is specified in pounds per
square inch (psi), in kilopascals (kPa) or in bar.
The tire pressure should only be corrected when
the tires are cold.
Cold tire pressure: the tires are cold when the
vehicle has been parked for at least 3 hours
without direct sunlight on the tires or the vehicle
has been driven for 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.
Weight of optional equipment: the combined
weight of the optional equipment weighing more
than the replaced standard parts and more than
5 lbs (2.3 kg). This optional equipment, such as
high-performance brakes, level control system, a
roof luggage rack or high-performance batteries,
is not included in the curb weight and the weight
of the accessories.
TIN (Tire Identification Number): a unique
identification number which can be used by a
tire manufacturer to identify tires, for example,
in 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 is a
code that contains the maximum load-bearing
capacity of a tire.
Traction: traction is the grip resulting from fric‐
tion between the tires and the road surface.
Wear indicator: narrow bars (tread wear bars)
that are distributed over the tire contact surface.
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 lb (68 kg)
multiplied by the number of seats in the vehicle.
Wheels and tires
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