Letter Rating; Speed Rating; Maximum Load Rating- Page 550

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Customer Information and Reporting Safety Defects

Tire Information (U.S.A.)

H

“H” is the speed rating. The speed rating denotes the maximum speed for which the use of 

the tire is rated.

Letter Rating

Speed Rating

Q

99 mph

R

106 mph

S

112 mph

T

118 mph

U

124 mph

H

130 mph

V

149 mph

W

168

*

 mph

Y

186

*

 mph

*

 For tires with a maximum speed capability over 149 mph, tire manufacturers sometimes 

use the letters ZR. For tires with a maximum speed capability over 186 mph, tire 

manufacturers always use the letters ZR.

M    S or M/S: Mud and Snow

AT: All Terrain.

AS: All Season. The “M S” or “M/S” indicates that the tire has some functional use in mud 

and snow.

U.S. DOT Tire Identification Number (TIN)

This begins with the letters “DOT” which indicates 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 manufactured. For example, the numbers 

457 means the 45st week of 1997. After 2000 the numbers go to four digits. For example, 

the number 2102 means the 21th week of 2002. The other numbers are marketing codes 

used at the manufacturer's discretion. This information is used to contact consumers if a tire 

defect requires a recall.

Tire Ply Composition and Materials Used

The number of plies indicates the number of layers of rubber-coated fabric in the tire. 

In general, the greater the number of plies, the more weight a tire can support. Tire 

manufacturers also must indicate the tire materials, which include steel, nylon, polyester, 

and other.

Maximum Load Rating

This number indicates the maximum load in kilograms and pounds that can be carried by the 

tire.

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