A tire is measured by width in millimeters from side wall to side wall, aspect ratio, which is the cross section height of the tire to the width, and wheel diameter. The markings on the tire display all the measurements, the type of tire, load capacity and speed rating.
Consumers who want to know the measurements of their tires can put away the tape measure and look for the codes written on the tire itself to get their answers. Below is a simple way to locate the tire's measurements. The first letter found in the tire is the tire type, either a P for P-metric, an E for Euro metric or LT for light truck. The characters following the type offer size and other information.
The tire width is indicated on the tire by the first three numbers. Because the measurement is done in millimeters, if the numbers were 215, it would mean the measurement was 215 millimeters.
When looking for the tires aspect ration, the two-digit number after the slash on the tire is the answer. If a tire has a height that is equal to 65 percent of the tire's width, the number displayed on the tire after the slash would be 65.
The last set of characters on the tire contains a letter representing the construction of the tire, such as "R" for radial, and the last two numbers after that tell the size of wheel that the tire will fit. A 15, for example, would mean the tire would fit on a 15-inch diameter wheel.