ElpiAuto275/55R20 vs 315/60R20
315/60R20 is 2.97″ (75 mm) taller than 275/55R20, a 9.3% difference in overall diameter — outside the ±3% band, so expect the speedometer to drift and check for rubbing before fitting.
| Measurement | 275/55R20 | 315/60R20 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 31.91″ | 34.88″ | +2.97″ | +9.3% |
| Section width | 10.83″ | 12.40″ | +1.57″ | +14.5% |
| Sidewall height | 5.95″ | 7.44″ | +1.49″ | +25.0% |
| Circumference | 100.25″ | 109.58″ | +9.34″ | +9.3% |
| Revs per mile | 632.0 | 578.2 | −53.9 | −8.5% |
| Revs per km | 392.7 | 359.3 | −33.5 | −8.5% |
Speedometer: with 275/55R20 as the original, 315/60R20 makes an indicated 60 mph really about 65.6 mph, and the axle sits ~1.49″ higher.
Reading this comparison
The overall diameter is what matters here: 315/60R20 is the taller tire. It sets ride height, gearing and how far the tire travels per revolution — which is what the speedometer and odometer count. Width and sidewall change fit and feel (a wider tire needs a wider wheel and more clearance; a shorter sidewall sharpens steering) but not the gearing.
Figures are geometric estimates from the size codes; real moulded tires vary by brand by 1–3%. Confirm load rating, wheel width and physical clearance on your vehicle before fitting. To compare any other two sizes, use the tire size comparison tool; to decode one size and see what else fits its wheel, the tire size calculator.