A tire size chart is used to translate the letters and numbers found on a tire's sidewall and contains information about tire class, width, aspect ratio, construction and wheel diameter. If you aren't familiar with reading the tire codes, it's easiest to write down the numbers and then compare them.
In the example P215/65R15 95H, the P means the tire is rated for general passenger use. LT would mean the tire is suited for light trucks and usually has a higher inflation rating.
The 215 is the tire width, measured in millimeters from one sidewall to the other. The 65 is the ratio of tire height to width. This number is separated from the tire width by a slash line. In this case, the height of this tire measures 65 percent of the tire width.
The R stands for radial tire. The layers are wrapped at a right angle to the tread of the tire. A tire with diagonal bias ply, which runs in a diagonal pattern, has a D label. The 15 is the diameter of the wheel, measured from end to end.
The 95 is the load index, or the amount of weight the tire can support when properly inflated. A tire with a 95 rating can support between 1433 and 1565 pounds. The H is a speed rating; in this case the tire can handle speeds of up to 130 miles per hour. A speed rating chart gives ratings for spare tires, winter tires, truck tires and performance cars.