65
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This two-digit number, known as the aspect ratio, gives the tire's ratio of height to width. Numbers
of 70 or lower indicate a short sidewall for improved steering response and better overall handling on dry
pavement.
R
The "R" stands for radial. Radial ply construction of tires has been the industry standard for the past 20 years.
Next number
This two-digit number is the wheel or rim diameter in inches. If you change your wheel size, you
will have to purchase new tires to match the new wheel diameter.
Next number
This two- or three-digit number is the tire's load index. It is a measurement of how much weight
each tire can support. You may find this information in your owner's manual. If not, contact a local tire dealer.
Note: You may not find this information on all tires because it is not required by law.
M+S
The "M+S" or "M/S" indicates that the tire has some mud and snow capability. Most radial tires have these
markings; hence, they have some mud and snow capability.
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.
1.5.9.2. UTQGS Information
Treadwear Number
This number indicates the tire's wear rate. The higher the treadwear number is, the longer
it should take for the tread to wear down. For example, a tire graded 400 should last twice as long as a tire
graded 200.
Traction Letter
This letter indicates a tire's ability to stop on wet pavement. A higher graded tire should allow
you to stop your car on wet roads in a shorter distance than a tire with a lower grade. Traction is graded from
highest to lowest as "AA","A", "B", and "C".
Temperature Letter
This letter indicates a tire's resistance to heat. The temperature grade is for a tire that is
inflated properly and not overloaded. Excessive speed, underinflation or excessive loading, either separately or
in combination, can cause heat build-up and possible tire failure. From highest to lowest, a tire's resistance to
heat is graded as "A", "B", or "C".
1.5.9.3. Additional Information on Light Truck Tires
Please refer to the following diagram.
Tires for light trucks have other markings besides those found on the sidewalls of passenger tires.
LT
The "LT" indicates the tire is for light trucks or trailers.
ST
An "ST" is an indication the tire is for trailer use only.
