| Air
Pressure: |
|
The amount of air inside the tire pressing outward
on each square inch of tire; expressed in pounds per square inch (psi)
or kiloPascals (kPa), the metric designation
for air pressure. |
| Alignment:
|
The state in which all wheels on a vehicle are
pointed in the optimum direction relative to the road and each
other. |
| All-Season
Tires:
|
Tires that are designed for use on dry and wet
pavement, and also provide traction in snow and ice. |
| Alphanumeric:
|
A term for describing the size of a tire in which
both letters of the alphabet and numbers are used. |
| Aramid:
|
A synthetic fabric used in some tires that is
(pound-for-pound) stronger than steel. |
| Aspect
Ratio:
|
The relationship of a tire's height to its width. |
| Balance:
|
The state in which a tire and wheel spin with all
their weight distributed equally. |
| Bead:
|
A round hoop of steel wires, wrapped or reinforced
by ply cords, that is shaped to fit the rim; holds the tire onto
the rim. |
| Belted
Bias Tire:
|
A pneumatic tire with a body similar to that of
bias tires, but which also includes two or more belts under the
tread. |
| Belt:
|
A rubber-coated layer of cords that is located
between the plies and the tread. Cords may be made from steel,
fiberglass, rayon, nylon, polyester or other fabrics. |
| Bias
Ply Tire:
|
A pneumatic tire in
which the plies are laid at alternate angles less than 90 degrees
to the center line of the tread. Plies usually run at angles about
30-40 degrees to the center line in a criss-cross fashion. |
| Carcass:
|
The tire body beneath the tread and sidewalls; also
called casing. |
| Cold
Inflation Pressure:
|
The amount of air pressure in a tire, measured in
pounds per square inch (psi) before a tire has built up heat from
driving. |
| Cord:
|
The strands of fabric forming the plies or layers
of the tire. Cords may be made from fiberglass, rayon, nylon,
polyester or steel. |
| DOT
Markings:
|
A code molded into the sidewall of a tire
signifying that the tire complies with U.S. Department of
Transportation motor vehicle safety standards. The DOT code
includes an alphanumeric designator which can also identify the
tire's manufacturer, production plant, date of production and
brand. |
| Footprint:
|
That portion of the tread that contacts the road. |
| Friction:
|
The force between the tires and the road surface
which causes the tire to grip the road. |
| Groove:
|
The space between two adjacent tread ribs; also
called tread grooves. |
| GVW |
Gross Vehicle Weight (GVW): The weight of the vehicle
including passengers, options and all cargo. |
| Highway
Tires:
|
Also called summer tires; designed for
wet-and-dry weather driving, but not for use on snow and ice. |
| Hydroplaning:
|
A skimming effect caused by tires losing contact
with a surface covered with water. |
| Innerliner:
|
The innermost layer of a tubeless tire. The
innerliner prevents air from permeating through the tire. |
| Loaded
section height:
|
The height of the section of the tire that is
making contact with the road. |
| Load
Index:
|
An assigned number ranging from 0 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; found molded onto the sidewall. |
| Nominal
rim diameter:
|
The diameter of a tire rim, given in nearest whole
numbers (e.g. 15") |
| Overall
diameter:
|
The diameter of the inflated tire, without any
load. |
| Overall
width:
|
the distance between the outside of the two
sidewalls, including lettering and designs. |
| P-Metric:
|
Uniform designation of tire sizes, in metric
measurements originally introduced by American tire manufacturers
in 1977; commonly called "P-metric series." A typical
P-metric tire is P205/70R14 93S. |
| Plus-Sizing:
|
An option allowing drivers to customize their
vehicle by mounting low-profile tires on wider rims of one or two
inches greater diameter, usually enhancing vehicle appearance,
handling and performance. |
| Ply:
|
A rubber-coated layer of fabric containing cords
that run parallel to each other; extends from bead to bead and
goes between the innerliner and belts or tread. |
| PSI:
|
An abbreviation for pounds per square inch (psi). |
| Radial
Ply Tire:
|
A type of tire with plies arranged so cords in the
body run at 90 degree angles to the center line of the tread. |
| Rim:
|
A metal support for a tubeless tire or a tire and
tube assembly upon which the tire beads are seated. |
| Rim
width:
|
Distance between the two opposite inside edges of
the rim flanges. |
| Rolling
Resistance:
|
The force required to keep a tire moving at a
uniform speed. The lower the rolling resistance, the less energy
needed to keep a tire moving. |
| Rotation:
|
The changing of tires from front to rear or from
side-to-side on a vehicle according to a set pattern; provides
even treadwear. |
| Section
height:
|
The height of the tire, measured from
rim
to the outer tread. |
| Section
width:
|
The distance between outside of
sidewalls,
not including any lettering or designs. |
| Series:
|
Tires with the same aspect ratio, or relationship
of height to width inside the tire. |
| Shimmy:
|
Wobbling of wheels from side-to-side on a vehicle.
Shimmying can be caused by a variety of factors, including improperly
balanced tires, poor alignment and bent wheels. |
| Shoulder:
|
The area of a tire where the tread and sidewall
meet. |
| Sidewall:
|
That portion of a tire between the
tread
and the bead. |
| Sipes:
|
Special slits within a tread that increase wet and
snow traction. |
| Size:
|
The combination of tire width, construction type,
aspect
ratio and rim size used in differentiating tires. |
| Skid:
|
To slip or slide on the road when tires lose their
rolling grip. |
| Snow
Tire:
|
Sometimes called winter tire; a special type of
tire with a tread and compound that gives better traction in snow;
identified by the M+S, M&S, or M/S on the sidewalls. All-season
tires must also include these designations
on the sidewall. |
| Speed
Rating:
|
An alphabetical code (A-Z) assigned to a tire
indicating the range of speeds at which the tire can carry a load
under specified service conditions
. |
| Tire:
|
A precisely engineered assembly of rubber,
chemicals, fabric and metal designed to provide traction, cushion
road shock and carry a load under varying conditions. |
| Tire
Placard:
|
A metal or paper tag permanently affixed to a
vehicle which indicates the appropriate tire size and inflation
pressures for the vehicle. |
| Tramping:
|
A state in which a vehicle bounces up and down
abnormally. |
| Tread:
|
That portion of a tire that comes into contact with
the road. It is distinguished by the design of its ribs and
grooves. |
| Tread
Rib:
|
The tread section that runs around the
circumference of the tire, separated by the tread grooves. |
| Treadwear
Indicator:
|
Narrow bands, sometimes called "wear
bars," that appear across the tread of the tire when only
2/32 inch of tread remains. |
| Tread
width:
|
The width of a tire's tread. |
| Traction:
|
The friction between the tires and the road
surface; the amount of grip provided. |
| UTQGS:
|
(Uniform Tire Quality Grading Standards)
A tire information system that provides consumers with ratings
(from A to C) for a tire's traction and temperature. Treadwear is
normally rated from 60 to 620. Ratings are determined by tire
manufacturers using government-prescribed test procedures, and are
molded into the sidewall of the tire. |
| Valve:
|
A device that lets air in or out of a tire. Fitted
with a valve cap to keep out dirt and moisture and a valve core to
prevent air from escaping. |
| Wear
Bars:
|
See Treadwear Indicator. |
