Tire math reference
Terms of Service
Effective date: June 2026
Use of the service
TreadSize is provided free of charge for personal and professional informational use. You may use the calculators, guides, and reference pages for any lawful purpose.
No warranty
TreadSize provides tire size calculations based on standard ETRTO formulas. We make no warranty — express or implied — that the computed values are suitable for any specific vehicle, application, or jurisdiction. Tire fitment involves physical constraints (wheel well clearance, load rating, speed rating, offset, hub bore) that our tools do not assess.
Always confirm fitment with a qualified tire professional and your vehicle's owner's manual before purchasing or installing tires.
Limitation of liability
TreadSize and its operators shall not be liable for any damages arising from use of the information on this site, including but not limited to tire-fitment decisions, vehicle damage, or personal injury.
Affiliate links
When affiliate links are live (disclosed at the point of use), clicking them may result in us earning a commission if you make a purchase. This does not affect the calculations shown.
Contact
Questions: hello@treadsize.com
Sources, review and limits
Last verified
June 2026
Author and reviewer
Written by TreadSize editorial desk; reviewed by Automotive fitment review.
Primary data sources
- Tire size math from ISO-style tire notation formulas
- Original-equipment size references supplied by users or vehicle placards
- Fitment-risk thresholds documented in the calculator
Tire fitment output is a planning estimate. Wheel width, offset, suspension, load rating and local rules matter. Confirm OE specs and safe fitment with a tire professional before driving.