295/35R21 tyre size
A 295/35R21 tyre is 295 mm (11.6") wide with a sidewall height of 35 % of the width, i.e. 103.3 mm (4.1"), on a 21" (533 mm) rim. Overall diameter is 739.9 mm (29.1"), so the closest inch-style size is 29.1×11.6R21. Static circumference is 2324 mm; the ETRTO rolling circumference is 2257 mm, giving 443 revolutions per km (713 per mile).
Dimensions and rolling diameter
| Section width | 295 mm | 11.61″ |
| Sidewall height | 103.3 mm | 4.06″ |
| Rim diameter | 533.4 mm | 21″ |
| Overall diameter (static, unloaded) | 739.9 mm | 29.13″ |
| Static radius | 370.0 mm | 14.56″ |
| Static circumference (π × D) | 2,324 mm | 91.5″ |
| Rolling circumference (ETRTO 3.05 × D) | 2,257 mm | 88.8″ |
| Effective rolling radius | 359.2 mm | 14.14″ |
| Revs per km (rolling / static) | 443 / 430 | |
| Inch equivalent | 29.1×11.6R21 | |
| Approved rim widths (approx.) | 10″–11.5″ (measuring rim 10.5″) | |
A 295/35R21 tyre is 295 mm (11.6") wide with a sidewall height of 35 % of the width, i.e. 103.3 mm (4.1"), on a 21" (533 mm) rim. Overall diameter is 739.9 mm (29.1"), so the closest inch-style size is 29.1×11.6R21. Static circumference is 2324 mm; the ETRTO rolling circumference is 2257 mm, giving 443 revolutions per km (713 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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