265/70R17 tyre size
A 265/70R17 tyre is 265 mm (10.4") wide with a sidewall height of 70 % of the width, i.e. 185.5 mm (7.3"), on a 17" (432 mm) rim. Overall diameter is 802.8 mm (31.6"), so the closest inch-style size is 31.6×10.4R17. Static circumference is 2522 mm; the ETRTO rolling circumference is 2449 mm, giving 408 revolutions per km (657 per mile).
Dimensions and rolling diameter
| Section width | 265 mm | 10.43″ |
| Sidewall height | 185.5 mm | 7.30″ |
| Rim diameter | 431.8 mm | 17″ |
| Overall diameter (static, unloaded) | 802.8 mm | 31.61″ |
| Static radius | 401.4 mm | 15.80″ |
| Static circumference (π × D) | 2,522 mm | 99.3″ |
| Rolling circumference (ETRTO 3.05 × D) | 2,449 mm | 96.4″ |
| Effective rolling radius | 389.7 mm | 15.34″ |
| Revs per km (rolling / static) | 408 / 396 | |
| Inch equivalent | 31.6×10.4R17 | |
| Approved rim widths (approx.) | 7.5″–9″ (measuring rim 8″) | |
A 265/70R17 tyre is 265 mm (10.4") wide with a sidewall height of 70 % of the width, i.e. 185.5 mm (7.3"), on a 17" (432 mm) rim. Overall diameter is 802.8 mm (31.6"), so the closest inch-style size is 31.6×10.4R17. Static circumference is 2522 mm; the ETRTO rolling circumference is 2449 mm, giving 408 revolutions per km (657 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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