Federal law mandates that tire manufacturers place standardized information on the sidewall of all tires (see the
illustration).
The following information is listed on the tire sidewall:
The tire designation (the following figures are examples of a tire designation):
1. 215: the width of the tire (in millimeters) from sidewall edge to sidewall edge. The larger the number, the wider the
tire.
2. Å: The ratio of the tire's height to its width.
3. R: Radial tire.
4. 15: The diameter of the wheel rim (in inches).
5. 95: The tire's load index. In this example, a load index of 95 equals a maximum load of 1521 lbs (690 kg).
6. H : The tire's speed rating, or the maximum speed at which the tire is designed to be driven for extended periods of
time, carrying a permissible load for the vehicle, and with correct inflation pressure. For example, H indicates a speed
rating of 130 mph (210 km/h).
NOTE
This information may not appear on the tire because it is not required by law.
7. M+S or M/S = Mud and Snow
AT = All Terrain
AS = All Season
8. U.S. DOT Tire Identification Number (TIN): This begins with the letters "DOT" and indicates that the tire meets all
federal standards. The next two numbers or letters are the plant code where it was manufactured, the next two are the
tire size code and the last four numbers represent the week and year the tire was built. For example, the numbers 317
mean the 31st week of 1997. After 2000 the numbers go to four digits. For example, 2501 means the 25th week of
2001. The numbers in between are marketing codes used at the manufacturer's discretion. This information helps a tire
manufacturer identify a tire for safety recall purposes.
9. Tire Ply Composition and Material Used: Indicates the number of plies indicates or the number of layers of rubber-
coated fabric in the tire tread and sidewall. Tire manufacturers also must indicate the ply materials in the tire and the
sidewall, which include steel, nylon, polyester, and others.
10. Maximum Load: Indicates the maximum load in pounds and kilograms that can be carried by the tire. Refer to the
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Vehicle loading
WARNING
Exceeding the permissible axle weight, gross vehicle weight, or any other weight rating limits can cause tire
overheating resulting in permanent deformation or catastrophic failure.
Do not use replacement tires with lower load carrying capacities than the tires that were original equipment on the
vehicle because this will lower the vehicle's GVW rating. Replacement tires with a higher limit than the originals do
not increase the vehicle's GVW rating limitations.
168 07 Wheels and tires
Uniform Tire Quality Grading
ALL PASSENGER VEHICLE TIRES MUST CONFORM TO FEDERAL SAFETY REQUIREMENTS IN
ADDITION TO THESE GRADES
Quality grades can be found, where applicable, on the tire sidewall between the tread shoulder and maximum section
width. For example:
Treadwear 200 Traction AA Temperature A
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 course. For example, a tire graded 150 would wear one and one half (1 1/2) times as
well on the government course as a tire graded 100. The relative performance of tires depends upon the actual
conditions of their use, however, and many depart significantly from the norm due to variation in driving habits,
maintenance practices and differences in road characteristics and climate.
TRACTION
The traction grades, from highest to lowest, are AA, A, B, and C, as measured under controlled conditions on specified
government test surfaces of asphalt and concrete. A tire marked C may have poor traction performance.
WARNING
The traction grade assigned to this tire is based on braking (straight-ahead) traction tests and is not a measure of
cornering (turning) traction.
TEMPERATURE
The temperature grades are AA (the highest), A, B, and C, representing the tire's resistance to the generation of heat
and its ability to dissipate heat when tested under controlled conditions on a specified indoor laboratory test wheel.
Sustained high temperature can cause the material of the tire to degenerate and reduce tire life, and excessive
temperature can lead to sudden tire failure. The grade C corresponds to a minimum level of performance that all
passenger vehicle tires must meet under the Federal Motor Safety Standard No. 109. Grades B and A represent higher
levels of performance on the laboratory test wheel than the minimum required by law.
WARNING
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