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Maintenance
Temperature -A, B & C
The temperature grades are A (the
highest), B and C representing 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. Grades B and A
represent higher levels of perform-
ance on the laboratory 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
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
transaxle, power seats, and air con-
ditioning.
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: 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.
Maintenance
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Intended Outboard Sidewall : The
side of an asymmetrical tire, that
must always face outward when
mounted on a vehicle.
Kilopascal (kPa): The metric unit for
air pressure.
Load Index: An assigned number
ranging from 1 to 279 that corre-
sponds to the load carrying capacity
of a tire.
Maximum Inflation Pressure: The
maximum air pressure to which a
cold tire may be inflated. The maxi-
mum air pressure is molded onto the
sidewall.
Maximum Load Rating : The load
rating for a tire at the maximum per-
missible inflation pressure for that
tire.
Maximum Loaded Vehicle Weight:
The sum of curb weight; accessory
weight; vehicle capacity weight; and
production options weight.
Normal Occupant Weight: The
number of occupants a vehicle is
designed to seat multiplied by 68 kg
(150 pounds). Occupant Distribution
: Designated
seating positions.
Outward Facing Sidewall: The side
of a asymmetrical tire that has a par-
ticular side that faces outward when
mounted on a vehicle. The outward
facing sidewall bears white lettering
or bears manufacturer, brand, and/or
model name molding that is higher or
deeper than the same moldings on
the inner facing sidewall.
Passenger (P-Metric) Tire : A tire
used on passenger cars and some
light duty trucks and multipurpose
vehicles.
Recommended Inflation Pressure :
Vehicle manufacturer's recommend-
ed tire inflation pressure and shown
on the tire placard.
Radial Ply Tire : A pneumatic tire in
which the ply cords that extend to the
beads are laid at 90 degrees to the
centerline of the tread.
Rim: A metal support for a tire and
upon which the tire beads are seat-
ed.
Sidewall: The portion of a tire
between the tread and the bead. Speed Rating: An alphanumeric
code assigned to a tire indicating the
maximum speed at which a tire can
operate.
Traction: The friction between the
tire and the road surface. The
amount of grip provided.
Tread: The portion of a tire that
comes into contact with the road.
Treadwear Indicators: Narrow
bands, sometimes called "wear
bars," that show across the tread of a
tire when only 2/32 inch of tread
remains.
UTQGS: Uniform Tire Quality
Grading Standards, a tire information
system that provides consumers with
ratings for a tire's traction, tempera-
ture and treadwear. Ratings are
determined by tire manufacturers
using government testing proce-
dures. The ratings are molded into
the sidewall of the tire.
Vehicle Capacity Weight
: The num-
ber of designated seating positions
multiplied by 68 kg (150 lbs.) plus the
rated cargo and luggage load.
