Maker & Reference
Tire Size Conversion Calculator
Decode P-metric tire size (width/aspect-ratio-R-wheel) into inches. Compare two sizes for speedo error and clearance.
Overall diameter
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- Section width
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- Sidewall
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- Speedo error vs compare
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FAQ
What is the aspect ratio? +
Sidewall height as a percentage of section width. 285/70 means sidewall is 70% of 285mm = 199.5mm tall.
Plus-sizing rules? +
Stay within 3% overall diameter of OEM to avoid speedo/ABS issues and rubbing. Wider wheels with shorter sidewalls keep total diameter close.