Automotive
Tire size calculator
A tire size like 225/65R17 packs four numbers into one code, and every one of them changes how the tire fits, rolls, and reports your speed. This tire size calculator works both ways: enter the metric size and it converts to inches — overall diameter, sidewall height, section width, and revolutions per mile — or enter your current diameter, width, and rim size, and it sweeps the width and aspect combinations on that rim for sizes within the 3% fitment guideline, flagging the straight matches inside ±2% separately from the 2–3% outer options. The rim stays fixed because you already own the wheels; the speedometer shifts by about the same percentage as the diameter changes, and clearance on the actual vehicle is the final check before you buy.
Live calculator
Enter your details
Your estimate
Results
Rim diameter plus twice the sidewall height.
Speedometer and odometer shift with this number.
- Your size: 225/65R17 — 28.52 in overall, 8.86 in wide, 707 revs/mile.
- Match: 245/60R17 — 28.57 in (+0.2%), 9.65 in wide.
- Match: 215/70R17 — 28.85 in (+1.2%), 8.46 in wide.
- Match: 235/60R17 — 28.1 in (-1.5%), 9.25 in wide.
- Match: 195/75R17 — 28.52 in (0%), 7.68 in wide.
- Within ±2% keeps the speedometer, ABS, and transmission in factory tolerance; ±3% is the outer fitment guideline. Same rim throughout.
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How it works
- 01
Metric sizes decode directly: sidewall = width × aspect ÷ 100 in millimeters, overall diameter = rim + 2 × sidewall, and revolutions per mile = 63,360 ÷ (π × diameter) — then the calculator lists every size on the same rim within 3% of that diameter.
- 02
The inches direction holds your rim fixed and sweeps the width and aspect combinations on it, keeping every match within 3% of your target diameter — you already own the wheels, so the rim never changes.
- 03
Anything within 2% is a straight fit; 2–3% is the outer guideline, where the speedometer drifts by the same amount and wheel-well clearance needs a check.
Try a real scenario
35 in tall, 12.5 in wide, 20 in rim
InputsInches → matching sizes: 35 in diameter, 12.5 in width, 20 in rim
Result35×12.50R20 (the flotation size itself) plus 315/60R20 — 34.9 in overall, 12.4 in wide. Close: 325/60R20 and 295/65R20.
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