647
Maintenance
Traction - AA, A, B & C
The traction grades, from highest to
lowest, are AA, A, B and C. The
grades represent the tires ability to
stop on wet pavement as measured
under controlled conditions on spec-
ified government test surfaces of
asphalt and concrete. A tire marked
C may have poor traction perform-
ance.
Temperature -A, B & C
The temperature grades are A (the
highest), B and C. The grades repre-
sent the tire’s resistance to the gen-
eration of heat and its ability to dissi-
pate heat when tested under con-
trolled conditions on a specified
indoor laboratory test wheel.
Sustained high temperature can
cause the material of the tire to degen-
erate and reduce tire life, and exces-
sive temperature can lead to sudden
tire failure. Grade C corresponds to a
level of performance which all passen-
ger vehicle tires must meet under the
Federal Motor Vehicle Safety
Standard No. 109. Grades A and B
represent higher levels of perform-
ance on the laboratory test wheel than
the minimum required by the law.
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.
WARNING - Tire
temperature
The temperature grade for this
tire is established for a tire that
is properly inflated and not
overloaded. Excessive speed,
underinflation, or excessive
loading, either separately or in
combination, can cause heat
build-up and possible sudden
tire failure. This can cause loss
of vehicle control and serious
injury or death.
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