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Wheel size designation
Wheels are also marked with
important in
formation 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:
8.0J X 19
8.0 - Rim width in inches.
J - Rim contour designation.
19 - Rim diameter in inches.
Tire speed ratings
The chart below lists many of the
diff
erent 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
Symbol Maximum 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 tires. 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 1421 represents that
the tire was produced in the 14th
week of 2021.
4. Tire ply composition and material
The number of layers or plies of
rubber-coated fabric in the tire. Tire
manufacturers also must indicate the
materials in the tire, which include
steel, nylon, polyester, and others.
The letter “R” means radial ply
construction; the letter “D” means
diagonal or bias ply construction;
and the letter “B” means belted-bias
ply construction.
CN7 N HMA 9.indd 9-39 2021-09-08 9:30:23
