How to Read Tire Labels

Tire labels contain a great deal of important information.

In 2009, the National Highway Traffic Safety Administration created new standards for tire markings on passenger and light truck tires. Information includes not only the regular aspect ration, tire width and rim diameter, but also information about composition of the tire, load index, treadwear, traction and temperature grades. Here is what the markings mean.

Instructions

Passenger Tires

1. Start with the tire name on the outer ring. The next letter you come to after the name will be a “P” for passenger tire. The next three numbers are the width of the tire in millimeters.

2. Read the next number past the slash mark. That will be the ratio of height to width. This is the aspect ratio. The next letter will indicate whether the tire is a radial or not. The next pair of numbers will be the rim diameter code followed by a space and then two letters that represent the load index and an alphabetic speed symbol.

3. Skip the next gap and you will find a temperature rating of “A,” “B,” or “C” and a severe weather rating, if it has one. After these letters will be the name of the manufacturer.

4. Read the last three groups of numbers to determine first tread wear. The higher the number, the longer the tread will last. Next comes traction rating. The rating starts at “AA,” then “A,” then “B,” etc. The higher the rating, the shorter your stopping distance in wet weather. The next number is the temperature grade (A, B or C). The closer to A, the more heat resistance found in the tire.

5. Follow the small letters around the edge of the rims. Starting below the tire name, you will find the maximum permissible inflation pressure followed by the USDOT tire identification number, the tire ply, composition and materials used in manufacturing.

Light Truck

1. Start at the outside ring of numbers with the tire name. The next number group begins with the two letters “LT” for light truck. Again, the next 3 numbers are the width of the tire in millimeters.

2. Find the numbers immediately after the slash mark. This is the aspect ratio (height to width) of the tire. If the tire is a radial it will be followed by an “R,” then the two numbers representing the rim diameter.

3. Continue clockwise around the tire. The next letter represents the load index, followed by a load index and speed symbol. After the next gap is the temperature and any severe snow or weather condition rating it may have. Following the manufacturer's name going clockwise are maximum load weight used as a single- or dua-mounted tire, followed by the tire pressure at which those load weights are correct.

4. Start reading the inside of the two small rings below the tire name. You will find the sidewall cord type, ply and another marking for if its a radial, tubeless or tubed tire.

5. Continue reading the next set of letters going clockwise. This is the USDOT tire identification number followed by the tread cord and ply rating.

References

• Safecar.gov: Tires