TireOd · automotive geometry
Tire overall diameter calculator | TireOd
Know approximate overall diameter before checking clearance or comparing sizes
Result
sidewall_mm=width_mm*(aspect_pct/100); diameter_in=rim_in+2*sidewall_mm/25.4; diameter_mm=diameter_in*25.4
How to use this estimate
Estimate overall tire diameter from metric size code (section width, aspect ratio, rim). How it works: sidewall_mm=width_mm*(aspect_pct/100); diameter_in=rim_in+2*sidewall_mm/25.4; diameter_mm=diameter_in*25.4. Out of scope: load index / speed rating; vehicle clearance; OEM fitment approval; TPMS or pressure advice. This is an approximate screening estimate, not a substitute for manufacturer charts or a full engineering design. Does not certify code compliance; confirm manufacturer data where it applies.
Sources, methodology, and assumptions
Methodology
sidewall_mm=width_mm*(aspect_pct/100); diameter_in=rim_in+2*sidewall_mm/25.4; diameter_mm=diameter_in*25.4
Assumptions
Cylindrical sidewall approximation; Metric size code labeling. This is an approximate screening estimate, not a substitute for manufacturer charts or a full engineering design.
Out of scope
load index / speed rating; vehicle clearance; OEM fitment approval; TPMS or pressure advice
Sources
- NIST SP 811 — SI / inch conversions — NIST
- Tire size code geometry (section × aspect → sidewall; + rim) — Industry geometry identity
Last technically reviewed: 2026-09-11