Tire Size Converter (P-Metric)
P-metric (215/65R16) → overall diameter, revolutions/mile, sidewall height.
Result
Overall diameter
27.00 in
747 revs/mile · sidewall 5.50".
- Tire spec215/65R16
- Section width215 mm (8.46 in)
- Aspect ratio65%
- Sidewall height139.8 mm (5.50 in)
- Rim diameter16 in
- Overall diameter27.00 in
- Circumference84.84 in
- Revs / mile747
Step-by-step
- Sidewall mm = width × aspect/100 = 215 × 65/100 = 139.75 mm.
- Sidewall in = 139.75 / 25.4 = 5.50 in.
- Overall = rim + 2 × sidewall = 16 + 11.00 = 27.00 in.
- Revs/mi = 63360 / circumference = 747.
How to use this calculator
- Enter the three numbers from your tire sidewall.
- Read overall dia + revs/mile.
About this calculator
P-metric tire codes follow format Width/Aspect R Rim — like 215/65R16. Width is in millimeters; aspect is sidewall height as percentage of width (so 215 × 65% = 140mm sidewall); R = radial; rim diameter is inches. Overall diameter = rim + 2 × sidewall (in inches). Sized changes affect speedometer accuracy (revs/mile changes), gearing (effective ratio), and clearance. Stay within ±3% of stock diameter to avoid speedometer/ABS issues.
Frequently asked
P/passenger metric uses width × aspect × rim. LT (light truck): same format but reinforced. Flotation: 33×12.50R20 — direct OD × width × rim format.
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