Auto & Transport
Tire Size Calculator
Calculate and compare tire sizes
Formulas and edge cases are reviewed against authoritative references before publication. For methodology, editorial standards, or corrections, use the links below.
Frequently asked questions
What does the Tire Size Calculator do?
It helps you calculate and compare tire sizes.
What inputs do I need?
Enter Width, Aspect ratio, and Wheel diameter.
Are decimals supported?
Yes, you can use decimal values where appropriate.
Related tools
About this tool
Inputs
- Width
- Aspect ratio
- Wheel diameter
Results
- Base diameter
- Base circumference
- Base revs per mile
- Compare diameter
- Diameter difference
- Percent difference
- Actual speed at 60
Getting the right answer starts with the right formula. The Tire Size Calculator handles the computation so you can focus on the decision. Fill in width, aspect ratio and wheel diameter and the tool handles the rest, showing you base diameter, base circumference, base revs per mile and other key metrics within moments. Real-world driving conditions (temperature, terrain, driving style) always deviate from published specs.
Having a dedicated tool to calculate and compare tire sizes saves time you would otherwise spend searching for formulas or setting up a spreadsheet. Keep maintenance records; they affect resale value and help catch patterns before they become expensive repairs. If the result surprises you, revisit your inputs — a mistyped digit or wrong unit is usually the culprit. Engine horsepower can be estimated from torque: HP = Torque × RPM ÷ 5252. Fuel economy, tire sizing, and loan payments are the most common automotive numbers people need to check.