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 may 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 Your Vehicle on page 4-31.
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 and
shown on the tire placard. See Inflation - Tire Pressure
on page 5-58 and Loading Your Vehicle on page 4-31.
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 on page 5-64.
5-57