Wheels
Glossary of tire and loading
terminology
Accessory weight
means the combined weight (in
excess of those standard items
which may be replaced) of auto-
matic transmission, power steer-
ing, power brakes, power win-
dows, power seats, radio, and
heater, to the extent that these
items are available as factory-in-
stalled equipment (whether in-
stalled or not).
Aspect ratio
means the ratio of the height to
the width of the tire in percent.
Numbers of 55 or lower indicate a
low sidewall for improved steer-
ing response and better overall
handling on dry pavement.
Bead
means the part of the tire that is
made of steel wires, wrapped or
reinforced by ply cords and that is
shaped to fit the rim.
Bead separation
means a breakdown of the bond
between components in the bead.
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Cord
means the strands forming the
plies in the tire.
Cold tire inflation pressure
means the tire pressure recom-
mended by the vehicle manufac-
turer for a tire of a designated
size that has not been driven for
more than a couple of miles (kilo-
meters) at low speeds in the three
hour period before the tire pres-
sure is measured or adjusted.
Curb weight
means the weight of a motor ve-
hicle with standard equipment in-
cluding the maximum capacity of
fuel, oil, and coolant, air condi-
tioning and additional weight of
optional equipment.
Extra load tire
means a tire designed to operate
at higher loads and at higher in-
flation pressures than the corre-
sponding standard tire. Extra load
tires may be identified as “XL”,
“xl”, “EXTRA LOAD”, or “RF” on
the sidewall.
