09
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Example tire size designation:
(These numbers are provided as
an example only; your tire size
designator could vary depending on
your vehicle.)
235/55R19 105W
235 - Tire width in millimeters.
55 - Aspect ratio. The tire’s section
height as a percentage of its
width.
R - Tire construction code (Radial).
19 - Rim diameter in inches.
105 - Load Index, a numerical code
associated with the maximum
load the tire can carry.
W - Speed Rating Symbol. See
the speed rating chart in
this section for additional
information.
Wheel size designation
Wheels are also marked with
important information that you need
if you ever have to replace one. The
following explains what the letters
and numbers in the wheel size
designation mean.
Example wheel size designation:
7.5J X 19
7.5 - Rim width in inches.
J - Rim contour designation.
19 - Rim diameter in inches.
Tire speed ratings
The chart below lists many of the
different speed ratings currently
being used for passenger vehicle
tires. The speed rating is part of the
tire size designation on the sidewall
of the tire. This symbol corresponds
to that tire’s designed maximum safe
operating speed.
Speed Rating
SymbolMaximum Speed
S 112 mph (180 km/h)
T 118 mph (190 km/h)
H 130 mph (210 km/h)
V 149 mph (240 km/h)
W 168 mph (270 km/h)
Y 186 mph (300 km/h)
3. Checking tire life (TIN : Tire
Identification Number)
Any tires that are over six years old,
based on the manufacturing date,
(including the spare tire) should be
replaced by new ones. You can find
the manufacturing date on the tire
sidewall (possibly on the inside of
the wheel), displaying the DOT Code.
The DOT Code is a series of numbers
on a tire consisting of numbers and
English letters. The manufacturing
date is designated by the last four
digits (characters) of the DOT code.
DOT : XXXX XXXX OOOO
The front part of the DOT shows a
plant code number, tire size and
tread pattern and the last four
numbers indicate week and year
manufactured.
For example:
DOT XXXX XXXX 1522 represents that
the tire was produced in the 15th
week of 2022.
Maintenance
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Bias ply tire
A pneumatic tire in which the plies
are laid at alternate angles less than
90 degrees to the centerline of the
tread.
Cold tire pressure
The amount of air pressure in a tire,
measured in pounds per square inch
(psi) or kilopascals (kPa) before a tire
has built up heat from driving.
Curb weight
This means the weight of a motor
vehicle with standard and optional
equipment including the maximum
capacity of fuel, oil and coolant, but
without passengers and cargo.
DOT markings
A code molded into the sidewall
of a tire signifying that the tire
is in compliance with the U.S.
Department of Transportation motor
vehicle safety standards. The DOT
code includes the Tire Identification
Number (TIN), an alphanumeric
designator which can also identify
the tire manufacturer, production
plant, brand and date of production.
GVWR
Gross Vehicle Weight Rating
GAWR FRT
Gross Axle Weight Rating for the
Front Axle.
GAWR RR
Gross Axle Weight Rating for the
Rear axle.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.
Light Truck (LT) tire
A tire designated by its manufacturer
as primarily intended for use on
lightweight trucks or multipurpose
passenger vehicles.
Load ratings
The maximum load that a tire is rated
to carry for a given inflation pressure.
Load index
An assigned number ranging from 1
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. The
maximum air pressure is molded
onto the sidewall.
Maximum load rating
The load rating for a tire at the
maximum permissible inflation
pressure for that tire.
