What does 6.15R13 mean?

Tire sizes are easy to understand once you learn how to read them.  On this page you'll find a color-coded explanation of the 6.15R13 tire code.

6.15

This number indicates that your tire has a width of 6.15 inches.

R

This letter denotes how your tire was constructed.  Radial is the standard construction method for about 99% of all tires sold today.

RRadial
BBias Belt
DDiagonal
13

The tire size was designed to fit rims or wheels that are 13 inches in diameter.