225/65R17 tyre size
A 225/65R17 tyre is 225 mm (8.9") wide with a sidewall height of 65 % of the width, i.e. 146.3 mm (5.8"), on a 17" (432 mm) rim. Overall diameter is 724.3 mm (28.5"), so the closest inch-style size is 28.5×8.9R17. Static circumference is 2275 mm; the ETRTO rolling circumference is 2209 mm, giving 453 revolutions per km (729 per mile).
Dimensions and rolling diameter
| Section width | 225 mm | 8.86″ |
| Sidewall height | 146.3 mm | 5.76″ |
| Rim diameter | 431.8 mm | 17″ |
| Overall diameter (static, unloaded) | 724.3 mm | 28.52″ |
| Static radius | 362.2 mm | 14.26″ |
| Static circumference (π × D) | 2,275 mm | 89.6″ |
| Rolling circumference (ETRTO 3.05 × D) | 2,209 mm | 87.0″ |
| Effective rolling radius | 351.6 mm | 13.84″ |
| Revs per km (rolling / static) | 453 / 439 | |
| Inch equivalent | 28.5×8.9R17 | |
| Approved rim widths (approx.) | 6″–7.5″ (measuring rim 6.5″) | |
A 225/65R17 tyre is 225 mm (8.9") wide with a sidewall height of 65 % of the width, i.e. 146.3 mm (5.8"), on a 17" (432 mm) rim. Overall diameter is 724.3 mm (28.5"), so the closest inch-style size is 28.5×8.9R17. Static circumference is 2275 mm; the ETRTO rolling circumference is 2209 mm, giving 453 revolutions per km (729 per mile).
Why two circumferences? The static figure is simple geometry (π × diameter). Under load a radial tyre flattens and rolls about 3 % less per revolution; ETRTO defines the rolling circumference as 3.05 × the nominal diameter, which is what manufacturers quote and what speedo and gearing calculations should use.
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