Air Pressure: The amount of air inside the tire pressing outward on each square inch of the tire.
Air pressure is expressed in pounds per square inch (psi) or kilopascal (kPa).
Accessory Weight: This means the combined weight of optional accessories. Some examples of optional
accessories are, automatic transmission, power steering, power brakes, power windows,
power seats, and air conditioning.
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
kilopascals (kPa) before a tire has built up heat from driving. See
Inflation - Tire Pressure
.
Curb Weight: 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 (DOT) motor vehicle safety standards. The
DOT code includes the Tire Identification Number (TIN), an alphanumeric
designator which can also identify the tire manufacturer, production plant, brand,
and date of production.
GVWR: Gross Vehicle
Weight Rating. See
Loading the Vehicle
.
GAWR FRT: Gross
Axle Weight Rating for the front axle. See
Loading the Vehicle
.
GAWR RR: Gross
Axle Weight Rating for the rear axle. See
Loading the Vehicle
.
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.
Light Truck (LT-Metric) Tire: A tire used on light duty trucks and some multipurpose
passenger vehicles.
Load Index: An assigned number ranging from 1 to 279 that corresponds to the load carrying capacity
of a tire.
Maximum Inflation Pressure: The maximum air pressure to which a cold tire can be inflated. The maximum
air pressure is molded onto the sidewall.
Maximum Load Rating: The load rating for a tire at the maximum permissible 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 150 lbs (68 kg).
See
Loading the Vehicle
.
Occupant Distribution: Designated seating positions.
Outward Facing Sidewall: The side of an asymmetrical tire that has a particular side that faces outward when
mounted on a vehicle. The side of the tire that contains a whitewall, bears white
lettering, or bears manufacturer, brand, and/or model name molding that is higher
or deeper than the same moldings on the other sidewall of the tire.
Passenger (P-Metric) Tire: A tire used on passenger cars and some light duty trucks and multipurpose
vehicles.
Recommended Inflation Pressure: Vehicle manufacturer's recommended tire inflation pressure as shown
on the tire placard. See
Inflation - Tire Pressure
and
Loading the Vehicle
.
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 seated.
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 1/16 inch (1.6 mm) of tread remains. See
When It Is Time for New Tires
.
UTQGS (Uniform Tire Quality Grading Standards): A tire information system that provides consumers with
ratings for a tire's traction, temperature, and treadwear. Ratings are determined
by tire manufacturers using government testing procedures. The ratings are molded
into the sidewall of the tire. See
Uniform Tire Quality Grading
.
Vehicle Capacity Weight: The number of designated seating positions multiplied by 150 lbs (68 kg)
plus the rated cargo load. See
Loading the Vehicle
.
Vehicle Maximum Load on the Tire: Load on an individual tire due to curb weight, accessory weight, occupant
weight, and cargo weight.
Vehicle Placard: A label permanently attached to a vehicle showing the vehicle's capacity weight and
the original equipment tire size and recommended inflation pressure. See "Tire
and Loading Information Label" under
Loading the Vehicle
.