How it Works
((Width * Ratio / 100) * 2) / 25.4 + Rim.
What is Tire Size Calculator?
Sidewall height & total diameter.
Step-by-Step Guide
1. Spec
e.g. 225/45R17.
2. Calc
Geometry.
3. Diff
vs Old.
Example
Input: 225/45R17
Result: 25.0 inch
FAQ
First number?
Width in mm.
Conclusion
Keep diameter within 3% to avoid speedometer error.