Cold tire inflation pressure
The tire pressure recommended by the vehicle manufacturer for a tire of a specified size that has not
been driven for more than a couple of miles (kilometers) at low speeds in the 3 hour period before the
tire pressure is measured or adjusted.
Curb weight
The weight of a motor vehicle with standard equipment including the maximum capacity of fuel, oil,
and coolant, air conditioner, and additional weight of optional equipment.
Extra load tire
A tire designed to operate at higher loads and at higher inflation pressures than the corresponding
standard tire.
Gross Axle Weight Rating (GAWR)
The load-carrying capacity of a single axle system, measured where the tire contacts the ground.
Gross Vehicle Weight Rating (GVWR)
The maximum loaded weight of the vehicle.
Groove
The space between 2 adjacent tread ribs.
Load rating (code)
The maximum load that a tire is rated to carry for a given inflation pressure. You may not find this
information on all tires because it is not required by law.
Maximum load rating
The load rating for a tire at the maximum permissible inflation pressure for that tire.
Maximum loaded vehicle weight
The total of:
x Curb weight.
x Accessory weight.
x Vehicle capacity weight.
x Production options weight.
Maximum (permissible) inflation pressure
The maximum cold inflation pressure to which a tire may be inflated. Also called “maximum inflation
pressure.”
Normal occupant weight
Means 150 lbs (68 kilograms) times the number of occupants seated in the vehicle up to the total
seating capacity of your vehicle.
Occupant distribution
The placement of passengers in a vehicle.
Outer diameter
The diameter of a new, properly inflated tire.
Overall width
Total width measured at the exterior sidewalls of an inflated tire, including the additional width of
labeling, decorations, or protective bands or ribs.
Passenger car tire
A tire intended for use on passenger cars, multipurpose passenger vehicles, and trucks, that have a
gross vehicle weight rating (GVWR) of 10,000 pounds or less.
Ply
A layer of rubber-coated parallel cords.
Ply separation
A parting of rubber compound between adjacent plies.
Pneumatic tire
A mechanical device made of rubber, chemicals, fabric, and steel or other materials, that, when
mounted on an automotive wheel, provides the traction and contains the gas or fluid that sustains the
load.
Production options weight
The combined weight of installed regular production options weighing over 5 lbs (2.3 kg) more then the
standard items they replace, and not previously considered as curb weight or accessory weight. These
include, for example, heavy-duty brakes, ride levelers, roof rack, heavy-duty battery, and special trim.
Radial ply tires
A pneumatic tire in which the ply cords that extend to the beads are laid at substantially 90 degrees to
the centerline of the tread.
Recommended inflation pressure
The tire pressure recommended by the vehicle manufacturer for a tire of a specified size that has not
been driven for more than a couple of miles (kilometers) at low speeds in the 3 hour period before the
tire pressure is measured or adjusted.
Reinforced tire
A tire designed to operate at higher loads and at higher inflation pressures than the corresponding
standard tire.
Rim
The outer edge of a wheel upon which the tire beads are seated.
Rim diameter
The nominal diameter of the wheel's tire bead seating surface. If you change your wheel size, to
wheels of a different diameter, you will have to purchase new tires to match the new wheels.
Rim size
Designation means rim diameter and width.
Rim type designation
The industry or manufacturer's designation for a rim by style or code.
Rim width
The nominal distance between wheel rim flanges.
Section width
The linear distance between the exteriors of the sidewalls of an inflated tire, excluding elevations due
to labeling decoration, or protective bands.
Sidewall
The portion of a tire between the bead and the tread.
Wheel size designation
Wheel rim diameter and width.
Occupant loading and distribution for vehicle normal load for various designated seating
capacities
Designated seating capacity,
number of occupants
Vehicle normal load, number
of occupants
Occupant distribution in a
normally loaded vehicle
2, 3, or 4 2 2 in front
5 3 2 in front, 1 in back
Tires and vehicle load limits
