TireGeoCalcTire Size Alternatives Calculator
Enter one tire size. This tool searches standard metric widths and aspect ratios at the same rim diameter and lists the ones whose overall diameter stays within the tolerance you pick (2% or 3%), closest first. Everything is computed in your browser from the size you type. No account, no vehicle lookup, no personal data collected.
Find alternative tire sizes
| Size | Diameter | Diff | Rev/mile | Speedo @ 60 | Common | Notes |
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This tool computes geometry from the tire size text entered only and lists every standard size within tolerance at the same rim diameter (or, with the option above, one inch up or down), up to 40 results, closest first. "Common" marks the ordinary, widely-sold width/aspect/rim combinations; the size you entered may itself be common or not. It does not know your vehicle, does not inspect your tires, and does not look up manufacturer specifications.
Sources and limits
Every alternative on this page is a standard metric width/aspect combination computed from the tire size you entered by this site's geometry engine -- not a manufacturer fitment chart and not a claim that any listed size is interchangeable on a particular vehicle or wheel well. The 2-3% range is the tolerance commonly used as a guide for speedometer accuracy and ABS/traction-control wheel-speed sensing; it is not a safety threshold. Subaru publishes its own, tighter figure (overall circumference within about 6 mm -- NHTSA source 10205932); for every other make, check your vehicle's owner's manual and the wheel manufacturer's fitment guidance before changing tire size. Full limits are on the site disclaimer page. Compare two specific sizes directly with the tire size calculator.
How we calculate: formulas, rounding and reference sources.