747
Maintenance
Temperature -A, B & C
The temperature grades are A (the
highest), B and C, and represent the
tire's resistance to the generation of
heat and its ability to dissipate heat
when tested under controlled condi-
tions on a specified indoor laboratory
test wheel.
Sustained high temperature can
cause the material of the tire to
degenerate and reduce tire life, and
excessive temperature can lead to
sudden tire failure. The grade C cor-
responds to a level of performance
which all passenger car tires must
meet under the Federal Motor
Vehicle Safety Standard No. 109.
Grades B and A represent higher
levels of performance on the labora-
tory test wheel than the minimum
required by law.Tire terminology and definitions
Air Pressure:
The amount of air
inside the tire pressing outward on
the tire. Air pressure is expressed in
kilopascal (kPa) or pounds per
square inch (psi).
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
kilopascals (kPa) or pounds per
square inch (psi), 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.
