Terms of Use

These tools are free to use for working out tire sizes. By using them you accept the terms below.

The numbers are nominal

Every figure is nominal geometry computed from the standard tire-size formula. A real tire varies by maker and model, and with wear, load and pressure. A maker's spec sheet for one exact model outranks any calculator — including this one.

Not a fitment guarantee

A size comparison is information, not a promise that a tire fits your vehicle. Before buying, confirm the approved rim-width range, load index, speed rating and the physical clearance on your own vehicle. Buying decisions — and what follows from them — are yours.

Corrections

Pages are corrected when an error is found. If you spot one, tell us — corrections are the most useful email this site gets.

Using the content

Fine for personal use, and linking to any page is welcome. The calculations themselves are standard formulas; the presentation is ours.

Last updated November 12, 2026.