About

We calculate nominal dimensions from tire size codes and check selected sizes against published specifications from at least two tire manufacturers. Each comparison names the tire model, links to the manufacturer and records the date checked. We show differences rather than treating calculated geometry as a measurement. See how we calculate and verify numbers. Found a mistake? Report an error with the page URL, tire model and source.

This site runs a single tool -- a tire size calculator -- plus a set of reference guides about tire sizing, load index and speed rating. Everything the calculator does happens in your browser: the sizes you type are never sent to a server.

This site does not sell tires, does not represent any tire manufacturer, and does not tell you whether a tire "fits" or is "safe" for your vehicle. The calculator reports geometry -- diameter, circumference, revolutions per mile, speedometer error -- computed from the sizes you enter, nothing more. See the disclaimer for the full limits of what the calculator can and cannot tell you.

Any brand or tire-size name mentioned on this site is used only to describe or refer to that product (nominative fair use) -- this site is not affiliated with, sponsored by, or endorsed by any tire or vehicle manufacturer.

Who runs this site: Manduc S-V Emanuel Sorin PFA, a Sole trader (PFA) registered in Romania. See Contact and Privacy for how to reach the operator and how your data is handled.