235/55R17 tyre size
A 235/55R17 tyre is 235 mm (9.3") wide with a sidewall height of 55 % of the width, i.e. 129.3 mm (5.1"), on a 17" (432 mm) rim. Overall diameter is 690.3 mm (27.2"), so the closest inch-style size is 27.2×9.3R17. Static circumference is 2169 mm; the ETRTO rolling circumference is 2105 mm, giving 475 revolutions per km (764 per mile).
Dimensions and rolling diameter
| Section width | 235 mm | 9.25″ |
| Sidewall height | 129.3 mm | 5.09″ |
| Rim diameter | 431.8 mm | 17″ |
| Overall diameter (static, unloaded) | 690.3 mm | 27.18″ |
| Static radius | 345.2 mm | 13.59″ |
| Static circumference (π × D) | 2,169 mm | 85.4″ |
| Rolling circumference (ETRTO 3.05 × D) | 2,105 mm | 82.9″ |
| Effective rolling radius | 335.1 mm | 13.19″ |
| Revs per km (rolling / static) | 475 / 461 | |
| Inch equivalent | 27.2×9.3R17 | |
| Approved rim widths (approx.) | 6.5″–8.5″ (measuring rim 7.5″) | |
A 235/55R17 tyre is 235 mm (9.3") wide with a sidewall height of 55 % of the width, i.e. 129.3 mm (5.1"), on a 17" (432 mm) rim. Overall diameter is 690.3 mm (27.2"), so the closest inch-style size is 27.2×9.3R17. Static circumference is 2169 mm; the ETRTO rolling circumference is 2105 mm, giving 475 revolutions per km (764 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.
Buying tyres for your business?
Onyx Tyres supplies workshops, retailers and fleets across Australia at wholesale prices. Open a trade account to see stock and pricing and order online.