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Maintenance
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.
