265/40R22 tyre size
A 265/40R22 tyre is 265 mm (10.4") wide with a sidewall height of 40 % of the width, i.e. 106.0 mm (4.2"), on a 22" (559 mm) rim. Overall diameter is 770.8 mm (30.3"), so the closest inch-style size is 30.3×10.4R22. Static circumference is 2422 mm; the ETRTO rolling circumference is 2351 mm, giving 425 revolutions per km (685 per mile).
Dimensions and rolling diameter
| Section width | 265 mm | 10.43″ |
| Sidewall height | 106.0 mm | 4.17″ |
| Rim diameter | 558.8 mm | 22″ |
| Overall diameter (static, unloaded) | 770.8 mm | 30.35″ |
| Static radius | 385.4 mm | 15.17″ |
| Static circumference (π × D) | 2,422 mm | 95.3″ |
| Rolling circumference (ETRTO 3.05 × D) | 2,351 mm | 92.6″ |
| Effective rolling radius | 374.2 mm | 14.73″ |
| Revs per km (rolling / static) | 425 / 413 | |
| Inch equivalent | 30.3×10.4R22 | |
| Approved rim widths (approx.) | 9″–10.5″ (measuring rim 9.5″) | |
A 265/40R22 tyre is 265 mm (10.4") wide with a sidewall height of 40 % of the width, i.e. 106.0 mm (4.2"), on a 22" (559 mm) rim. Overall diameter is 770.8 mm (30.3"), so the closest inch-style size is 30.3×10.4R22. Static circumference is 2422 mm; the ETRTO rolling circumference is 2351 mm, giving 425 revolutions per km (685 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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