As of 2015, tire size charts are available to view online at Tire-Size-Conversion.com. This website also provides helpful information to decipher the meanings of the letters and numbers found on a tire.
Tire-Size-Conversion.com systematically categorizes its tire size charts by wheel size or diameter length. Tire sizes covered on the site range from 13-inch wheels up to 30-inch, and diameters range from 21 inches through 54 inches. The site also provides a tire size calculator for finding other measurements. A tire size comparison calculator is also provided, and it allows the user to compare two different tire sizes side by side.