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Maintenance
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Tire terminology and defini-
tions
Air Pressure: The amount of air
inside the tire pressing outward on
the tire. Air pressure is expressed in
pounds per square inch (psi) or kilo-
pascal (kPa).
Accessory Weight: This means the
combined weight of optional acces-
sories. Some examples of optional
accessories are, automatic transmis-
sion, power seats, and air condition-
ing.
Aspect Ratio: The relationship of a
tire's height to its width.
Belt: A rubber coated layer of cords
that is located between the plies and
the tread. Cords may be made from
steel or other reinforcing materials.
Bead: The tire bead contains steel
wires wrapped by steel cords that
hold the tire onto the rim.
Bias Ply Tire: A pneumatic tire in
which the plies are laid at alternate
angles less than 90 degrees to the
centerline of the tread.
Cold Tire Pressure: The amount of
air pressure in a tire, measured in
pounds per square inch (psi) or kilo-
pascals (kPa) before a tire has built
up heat from driving.
Curb Weight:This means the weight
of a motor vehicle with standard and
optional equipment including the
maximum capacity of fuel, oil and
coolant, but without passengers and
cargo.
DOT Markings: A code molded into
the sidewall of a tire signifying that
the tire is in compliance with the U.S.
Department of Transportation motor
vehicle safety standards. The DOT
code includes the Tire Identification
Number (TIN), an alphanumeric des-
ignator which can also identify the
tire manufacturer, production plant,
brand and date of production.
GVWR: Gross Vehicle Weight Rating
GAWR FRT: Gross Axle Weight
Rating for the front Axle.
GAWR RR: Gross Axle Weight
Rating for the rear axle.
