275/55R20 vs 275/60R20: Tire Size Comparison
275/55R20 has an overall diameter of 31.91 in (810.5 mm). 275/60R20 has an overall diameter of 32.99 in (838.0 mm), a difference of 1.08 in (27.5 mm) (3.39%). Both sizes mount on the same 20-inch wheel diameter at the same section width; 275/60R20 has a taller sidewall than 275/55R20 because of its higher aspect ratio (60 vs 55).
| Metric | 275/55R20 | 275/60R20 | Difference |
|---|---|---|---|
| Section width | 10.83 in (275.0 mm) | 10.83 in (275.0 mm) | 0.00 in (0.0 mm) |
| Sidewall height | 5.95 in (151.3 mm) | 6.50 in (165.0 mm) | 0.54 in (13.8 mm) |
| Overall diameter | 31.91 in (810.5 mm) | 32.99 in (838.0 mm) | 1.08 in (27.5 mm) (3.39%) |
| Revolutions per mile | 632.0 | 611.3 | -20.7 |
Speedometer effect
Because 275/60R20 has a larger overall diameter, a speedometer calibrated for 275/55R20 would under-read once 275/60R20 is fitted: an indicated 60 mph corresponds to about 62.0 mph actual, using the ratio of the two diameters (32.99 in (838.0 mm) / 31.91 in (810.5 mm)). This is the sizes' geometry only, not a manufacturer-measured rolling diameter or a specific vehicle's speedometer calibration.
Sources and limits
Every figure on this page comes from the two tire sizes entered, computed by this site's geometry engine -- not from a manufacturer specification or a claim that either size is interchangeable on any particular vehicle or wheel well. Check your vehicle's owner's manual and the wheel manufacturer's fitment guidance before changing tire size. Full limits are covered on the site disclaimer page. Compare your own sizes with the tire size calculator.