275/70R16 tyre size
A 275/70R16 tyre is 275 mm (10.8") wide with a sidewall height of 70 % of the width, i.e. 192.5 mm (7.6"), on a 16" (406 mm) rim. Overall diameter is 791.4 mm (31.2"), so the closest inch-style size is 31.2×10.8R16. Static circumference is 2486 mm; the ETRTO rolling circumference is 2414 mm, giving 414 revolutions per km (667 per mile).
Dimensions and rolling diameter
| Section width | 275 mm | 10.83″ |
| Sidewall height | 192.5 mm | 7.58″ |
| Rim diameter | 406.4 mm | 16″ |
| Overall diameter (static, unloaded) | 791.4 mm | 31.16″ |
| Static radius | 395.7 mm | 15.58″ |
| Static circumference (π × D) | 2,486 mm | 97.9″ |
| Rolling circumference (ETRTO 3.05 × D) | 2,414 mm | 95.0″ |
| Effective rolling radius | 384.2 mm | 15.12″ |
| Revs per km (rolling / static) | 414 / 402 | |
| Inch equivalent | 31.2×10.8R16 | |
| Approved rim widths (approx.) | 7.5″–9″ (measuring rim 8″) | |
A 275/70R16 tyre is 275 mm (10.8") wide with a sidewall height of 70 % of the width, i.e. 192.5 mm (7.6"), on a 16" (406 mm) rim. Overall diameter is 791.4 mm (31.2"), so the closest inch-style size is 31.2×10.8R16. Static circumference is 2486 mm; the ETRTO rolling circumference is 2414 mm, giving 414 revolutions per km (667 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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