Disclaimers
Informational use only
All content on TreadSize — including tire size calculations, speedometer error estimates, plus sizing recommendations, and guide content — is provided for informational purposes only. It does not constitute professional automotive or tire fitting advice.
Formula accuracy
Calculations use standard ETRTO (European Tyre and Rim Technical Organisation) formulas. These produce nominal values based on the size code. Actual tire dimensions vary by manufacturer, rim width, inflation pressure, and vehicle load. The displayed values are computed from the size string — not measured from any physical tire.
Fitment responsibility
Tire fitment involves many factors beyond diameter: load index, speed rating, wheel offset, hub bore, wheel-well clearance at full suspension travel, traction control and ABS system compatibility, and local regulations. TreadSize tools do not assess these factors.
You are solely responsible for verifying that any tire size is appropriate for your specific vehicle before purchasing or installing. Always consult a qualified tire professional.
No affiliation
TreadSize is not affiliated with any tire manufacturer, retailer, or automotive brand. Product names mentioned in guides are for identification purposes only.
Sources and calculation limits
Source note updated
June 2026
Calculation scope
Nominal dimensions from the size markings supplied. Vehicle installation is not verified.
Method and inputs
- Nominal geometry calculated from tire-size markings
- Original-equipment size references supplied by users or vehicle placards
- Diameter differences and theoretical rotation ratios; no installation approval
Calculated dimensions do not verify the tire model, load or speed rating, approved rim width, wheel offset, physical clearance, or vehicle systems. Confirm those against manufacturer specifications before installation.