Federal Motor Vehicle Safety
Standard No. 139. Grades B and A
represent higher levels of
performance on the laboratory
test wheel than the minimum
required by law.
Glossary of Tire Terminology
Tire label:
A label showing the
OE (Original Equipment) tire sizes,
recommended inflation pressure
and the maximum weight the
vehicle can carry.
Tire Identification Number
(TIN):
A number on the sidewall
of each tire providing information
about the tire brand and
manufacturing plant, tire size and
date of manufacture. Also referred
to as DOT code.
Inflation pressure:
A measure
of the amount of air in a tire.
Standard load:
A class of
P-metric or Metric tires designed
to carry a maximum load at 35 psi
(2.41 bar)[36 psi (2.5 bar) for
Metric tires]. Increasing the
inflation pressure beyond this
pressure will not increase the tire’s
load carrying capability.
Extra load:
A class of P-metric or
Metric tires designed to carry a
heavier maximum load at 41 psi
(2.8 bar)[42 psi (2.9 bar) for
Metric tires]. Increasing the
inflation pressure beyond this
pressure will not increase the tire’s
load carrying capability.
kPa:
Kilopascal, a metric unit of
air pressure.
PSI:
Pounds per square inch, a
standard unit of air pressure.
Cold tire pressure:
The tire
pressure when the vehicle has
been stationary and out of direct
sunlight for an hour or more and
prior to the vehicle being driven for
1 mi (1.6 km).
Recommended inflation
pressure:
The cold inflation
pressure found on the Safety
Compliance Certification Label
(affixed to either the door hinge
pillar, door-latch post, or the door
edge that meets the door-latch
post, next to the driver's seating
position) or Tire Label located on
the B-Pillar or the edge of the
driver’s door.
B-pillar:
The structural member
at the side of the vehicle behind
the front door.
Bead area of the tire:
Area of the
tire next to the rim.
Sidewall of the tire:
Area
between the bead area and the
tread.
Tread area of the tire:
Area of
the perimeter of the tire that
contacts the road when mounted
on the vehicle.
Rim:
The metal support (wheel)
for a tire or a tire and tube
assembly upon which the tire
beads are seated.
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Focus (CDH) Canada/United States of America, enUSA
Wheels and Tires
