Maintenance
9-40
Ply
A layer of rubber-coated parallel cords.
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.
Pneumatic options weight
The combined weight of installed regular
production options weighing over 5 lb.
(2.3 kg) in excess of the standard items
which they replace, not previously
considered in curb weight or accessory
weight, including heavy duty breaks, ride
levelers, roof rack, heavy duty battery,
and special trim.
Recommended Inflation Pressure
Vehicle manufacturer’s recommended
tire inflation pressure as 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 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 of tread remains.
UTQGS
Uniform Tire Quality Grading Standards
is 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.
Vehicle Capacity Weight
The number of designated seating
positions multiplied by 150 lbs. (68 kg)
plus the rated cargo and luggage load.
Vehicle Maximum Load on the Tire
Load on an individual tire due to curb
and accessory weight plus maximum
occupant and cargo weight.
Vehicle Normal Load on the Tire
Load on an individual tire that is
determined by distributing to each axle
its share of the curb weight, accessory
weight, and normal occupant weight and
dividing by 2.
Vehicle Placard
A label permanently attached to a vehicle
showing the original equipment tire size
and recommended inflation pressure.
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