How do I read the information on the tire sidewall?

    One of the more common sidewall markings is metric. You might see sidewalls that look like the image to the right. 170/60ZR-17 or 170/60-17 72 ZR

    294A6374 600 px How to Read Tire Sidewall

     

    LabelDescription
    170170 mm. Section width, the width of the tire in millimeters (mm), measured from sidewall to sidewall. Since this measure is affected by the width of the rim, the measurement is for the tire when it is on its intended rim size.
    6060%. Aspect ratio, tells you the height of the tire, from the bead to the top of the tread. This is described as a percentage of the tire width. In our example, the aspect ratio is 60, so the tire’s height is 60 percent of its width. The smaller the aspect ratio, the wider the tire in relation to its height.
    ZRZR. Speed Rating, tire can be ridden over 149 mph (240 km/h) for sustained periods of time. Most other speed ratings indicate a maximum sustained speed.
    1717 inches. Rim diameter, this number specifies, in inches, the wheel rim diameter the tire is designed for. This is the diameter of the wheel in inches where the beads of the tire sit on the wheel. This measurement does not include the rim flange, so don’t measure from the outside of the rim.
    7272 load index. The load index indicates how much load the tire can carry.

    Another sidewall marking pattern is alphabetical.

    M T 90 – 17 Load Range B

    LabelDescription
    MM = Motorcycle code.
    TT = Tire Width code.
    9090%. Aspect ratio, tells you the height of the tire, from the bead to the top of the tread. This is described as a percentage of the tire width. In our example, the aspect ratio is 90, so the tire’s height is 90 percent of its width. The smaller the aspect ratio, the wider the tire in relation to its height.
    1717 inches. Rim diameter, this number specifies, in inches, the wheel rim diameter the tire is designed for. This is the diameter of the wheel in inches where the beads of the tire sit on the wheel. This measurement does not include the rim flange, so don’t measure from the outside of the rim.
    Load Range BThe load range indicates how much load the tire can carry.

    Another sidewall marking pattern is in inches.

    4.50 ZR 17 4PR

    LabelDescription
    4.504.50 inches. Section width, the width of the tire in inches, measured from sidewall to sidewall. Since this measure is affected by the width of the rim, the measurement is for the tire when it is on its intended rim size.
    ZRZR. Speed Rating, tire can be ridden over 149 mph (240 km/h) for sustained periods of time. Most other speed ratings indicate a maximum sustained speed.
    1717 inches. Rim diameter, this number specifies, in inches, the wheel rim diameter the tire is designed for. This is the diameter of the wheel in inches where the beads of the tire sit on the wheel. This measurement does not include the rim flange, so don’t measure from the outside of the rim.
    4PR4PR – Casing Strength (Ply Rating). The casing strength or ply rating refers to the tire load index. The PR marking is now only applied by the Japanese standard (JATMA). The Japanese standard can be compared to the European standard as follows: 4PR = normal version, 6PR = reinforced version. The PR number does not refer to the number of plies in the tire.