1213 1200.01
29
Speed Rating
The speed rating denotes the speed at which a tire is designed to be driven for extended
periods of time. The ratings range from 99 miles per hour (mph) to 186 mph. These ratings are
listed below. Note: You may not find this information on all tires because it is not required by
law.
* For tires with a maximum speed capability over 149 mph, tire manufacturers sometimes use
the letters ZR. For those with a maximum speed capability over 186 mph, tire manufacturers
always use the letters ZR.
U.S. DOT Tire Identification Number
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 3197
means the 31st week of 1997. 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 materials in the tire, which include steel, nylon, polyester,
and others.
Maximum Load Rating
This number indicates the maximum load in kilograms and pounds that can be carried by the
tire.
Maximum Permissible Inflation Pressure
This number is the greatest amount of air pressure that should ever be put in the tire under
normal driving conditions.
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
