Understanding Tire Markings
Understanding Tire Markings
Federal law requires tire manufacturers to place standardized information on the sidewall of all tires. This information identifies and describes the fundamental characteristics of the tire and also provides the tire identification number (TIN) for safety standard certification and in case of a recall.
1. Treadwear grade
This number indicates the tire's wear rate. See Uniform Tire Quality Grading.
2. Traction grade
This letter indicates a tire's ability to stop on wet pavement. See Uniform Tire Quality Grading.
3. Temperature grade
This letter indicates a tire's heat resistance grading. See Uniform Tire Quality Grading.
4. Tire category
P indicates the tire is a P-Metric type, designated for passenger vehicles, following the design standards of the U.S. Tire & Rim Association (T&RA). Tires without the P designation are Euro-Metric type, following the design standards of the European Tyre & Rim Technical Organization (ETRTO).
5. Tire width
This three-digit number gives the width in millimeters of the tire section, as defined from sidewall edge to sidewall edge
6. Aspect ratio
This two-digit number, also known as the profile, gives the sidewall height as a percentage of the section width. So, if the section width is 205 mm, and the aspect ratio is 50, the sidewall height will be 102 mm.
7. Tire construction
R indicates that the tire is of Radial ply construction.
8. Wheel diameter
This two-digit number is the diameter of the wheel rim in inches.
9. Load index
This two- or three-digit number is the tire's load index. It is a measurement of how much weight each tire can support. This number is not always shown.
10. Speed rating
The speed rating, when stated, denotes the maximum speed at which the tire should be used for extended periods. The ratings range from 99 mph(160 km/h) to 186 mph(300 km/h). These ratings are listed in the following table.
|
Rating |
Speed (mph) |
Speed (km/h) |
|
Q |
99 |
160 |
|
R |
106 |
170 |
|
S |
112 |
180 |
|
T |
118 |
190 |
|
U |
124 |
200 |
|
H |
130 |
210 |
|
V |
149 |
240 |
|
W |
168 |
270 |
|
Y |
186 |
300 |
11. Tire installation marking
Indicates the direction of wheel travel or the orientation of how the tire must be installed on the wheel rim. See Asymmetric non-directional tires.
12. Maximum tire load
This is the maximum load which can be carried by the tire.
13. Maximum permissible inflation pressure
The maximum inflation pressure for the tire. This pressure should not be used for normal driving.
14. 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, and the last four numbers represent the week and year the tire was built. For example, the numbers 1706 means the 17th week of 2006. The other numbers are marketing codes used at the manufacturer's discretion. This information can be used to contact consumers if a tire defect requires a recall.
15. International tire approval marks
16. Tire composition and materials
The number of plies in both the tread area, and the sidewall area, indicates how many layers of rubber coated material make up the structure of the tire. Information is also provided on the type of materials used.