Your tire has very useful information molded into the sidewall. It shows the name
of the tire, its size, whether it is a tubeless or tube type, the maximum load and
maximum inflation, the important safety warning and much other information.
Shown is the sidewall of a popular “P-metric,” speed rated auto tire. “P” stands
for passenger; “215” represents the width of the tire in millimeters; “65” is the
ratio of height to width; “R” means radial; “15” is the nominal rim diameter code;
and “95H” is the optional service description that consists of the load index (95)
and the speed symbol (H). Some older speed-rated tires may include the speed symbol
immediately before the “R” instead of showing a service description.
A “B” in place of the “R” means the tire is belted bias construction. A “D” in place
of the “R” means diagonal bias construction. “M+S” with the mountain/snowflake symbol
is the designation that the tire meets the RMA definitions for use in severe snow
conditions.
The maximum load is shown in kg (kilograms) and in lbs (pounds), and maximum pressure
in kPa (kilopascals) and in psi (pounds per square inch).
The letters “DOT” certify compliance with all applicable safety standards established
by the Department of Transportation (DOT). Adjacent to this is a tire identification
or serial number. This serial number is a code with up to 12 digits that are a combination
of numbers and letters. The last characters are numbers identifying the week and
year of manufacture. (Example: “1501” means fifteenth week of the year 2001.)
The sidewall also shows the type of cord and number of plies in the sidewall and
under the tread.
The DOT requires tire manufacturers to grade passenger car tires based on three
performance factors: treadwear, traction and temperature resistance.
Treadwear
The treadwear grade is a comparative rating based on the wear rate of the tire when
tested under controlled conditions on a specified government test track. A tire
graded 200 would wear twice as long on the government test course under the specified
test conditions as one graded 100. It is wrong to link treadwear grades with your
projected tire mileage. The relative performance of tires depends upon the actual
conditions of their use and may vary due to driving habits, service practices, differences
in road characteristics and climate.
Traction
Traction grades, from highest to lowest, are AA, A, B and C. They represent the
tire’s ability to stop on wet pavement as measured under controlled conditions on
specified government test surfaces of asphalt and concrete.
Temperature
The temperature grades, from highest to lowest, are A, B and C. These represent
the tire’s resistance to the generation of heat when tested under controlled conditions
on a specified indoor laboratory test wheel.
Light Truck Tires
Shown is typical information on the sidewall of a light truck tire.
“LT” stands for Light Truck, “LT235/85R16” is the size designation for a metric
light truck tire.
“M+S” with the mountain/snowflake symbol is the designation that the tire meets
the RMA definition for use in severe snow conditions.
“LOAD RANGE D” identifies the load and inflation limits; RADIAL indicates that the
tire has a radial construction. “MAX LOAD SINGLE 1192 kg (2623 lbs) AT 1470 kPa
(65 psi) COLD” indicates the maximum load rating of the tire and corresponding minimum
cold inflation pressure for that load when used as a single. For normal operation,
follow pressure recommendations in owner’s manual or on vehicle placard; “MAX LOAD
DUAL 1082 kg (2381 lbs) AT 1470 kPa (65 psi) COLD” indicates the maximum load rating
of the tire and corresponding minimum cold inflation pressure when used in a dual
configuration. The other markings on the sidewall have the same meaning as described
for the passenger car tire.
* For tires having a maximum speed capability above 149 mph (240 km/h) a “ZR” may
appear in the size designation. For tires having a maximum speed capability above
186 mph (300 km/h), a “ZR” must appear in the size designation. Consult tire manufacturer
for maximum speed when there is no Service Description. Example: P275/40R17 93W
at 168 mph (270 km/h) or P275/40ZR17 at above 149 mph (240 km/h). Consult tire manufacturer.
** A “ZR” may appear in the tire size designation.
NOTE: For “V”, “W”, or “Y”, and ties with a “ZR” rating, a vehicle load adjustment
(for speed) is required; consult tire manufacturer.