225/35R19 tyre size
A 225/35R19 tyre is 225 mm (8.9") wide with a sidewall height of 35 % of the width, i.e. 78.8 mm (3.1"), on a 19" (483 mm) rim. Overall diameter is 640.1 mm (25.2"), so the closest inch-style size is 25.2×8.9R19. Static circumference is 2011 mm; the ETRTO rolling circumference is 1952 mm, giving 512 revolutions per km (824 per mile).
Dimensions and rolling diameter
| Section width | 225 mm | 8.86″ |
| Sidewall height | 78.8 mm | 3.10″ |
| Rim diameter | 482.6 mm | 19″ |
| Overall diameter (static, unloaded) | 640.1 mm | 25.20″ |
| Static radius | 320.0 mm | 12.60″ |
| Static circumference (π × D) | 2,011 mm | 79.2″ |
| Rolling circumference (ETRTO 3.05 × D) | 1,952 mm | 76.9″ |
| Effective rolling radius | 310.7 mm | 12.23″ |
| Revs per km (rolling / static) | 512 / 497 | |
| Inch equivalent | 25.2×8.9R19 | |
| Approved rim widths (approx.) | 7.5″–9″ (measuring rim 8″) | |
A 225/35R19 tyre is 225 mm (8.9") wide with a sidewall height of 35 % of the width, i.e. 78.8 mm (3.1"), on a 19" (483 mm) rim. Overall diameter is 640.1 mm (25.2"), so the closest inch-style size is 25.2×8.9R19. Static circumference is 2011 mm; the ETRTO rolling circumference is 1952 mm, giving 512 revolutions per km (824 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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