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Tire Size Calculator

Overall diameter, sidewall height, and circumference from a tire code.

Section width (205 in 205/55R16)

Aspect ratio (55 in 205/55R16)

Rim diameter (16 in 205/55R16)

inch

How it works

Sidewall height = section width × aspect ratio ÷ 100. Overall diameter = 2 × sidewall + rim diameter × 25.4. Keep a new tire within about 3% of the original diameter so the speedometer stays accurate.

FAQ

Is this calculator free?

Yes. No signup is needed and nothing you enter is stored.

Is the result exact?

Results are rounded for display. For financial, medical, or legal decisions, confirm with a professional.

Do my numbers leave my device?

No. The calculation runs in your browser.