What is the Tire Size Calculator?
Calculate tire diameter, circumference and revolutions per mile from a size like 225/65R17. Know what a trip or a vehicle really costs. These auto and travel calculators cover fuel, charging, depreciation and the true per-mile cost of driving for commuters and professional drivers.
How to use the Tire Size Calculator
- Enter your width, your aspect ratio, your rim diameter.
- Results update automatically as you type; you can also press Calculate.
- Read the output: overall diameter, sidewall height, circumference, revolutions per mile.
- Use the 📊 chart to see the result visually, then copy or share it.
Formula and method
Worked example
With width = 225 mm, aspect ratio = 65 %, rim diameter = 17 in, the Tire Size Calculator returns overall diameter: 28.52 in; sidewall height: 5.76 in; circumference: 89.58 in.
Tips for better results
- Use your real-world fuel economy rather than the window sticker.
- Depreciation is often the largest hidden cost of owning a car.
- Gig drivers should track every mile — it changes net hourly pay dramatically.
Frequently asked questions
What does the Tire Size Calculator do?
Calculate tire diameter, circumference and revolutions per mile from a size like 225/65R17.
How is it calculated?
The Tire Size Calculator uses this method: Diameter = Rim + 2 × (Width × Aspect ÷ 25.4).
Can you show an example?
With width = 225 mm, aspect ratio = 65 %, rim diameter = 17 in, the Tire Size Calculator returns overall diameter: 28.52 in; sidewall height: 5.76 in; circumference: 89.58 in.
Is the Tire Size Calculator accurate?
Yes. It uses standard formulas and exact constants, and the results are verified by our automated test suite. Values are displayed to up to 12 significant digits.
Is this tool free and private?
Yes — the Tire Size Calculator is completely free with no sign-up, and it runs entirely in your browser, so the values you enter are never uploaded to our servers.
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