ElpiAuto315/60R20 vs 33X12.50R20
33X12.50R20 is 1.88″ (48 mm) shorter than 315/60R20, a 5.4% difference in overall diameter — outside the ±3% band, so expect the speedometer to drift and check for rubbing before fitting.
| Measurement | 315/60R20 | 33X12.50R20 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 34.88″ | 33.00″ | −1.88″ | −5.4% |
| Section width | 12.40″ | 12.50″ | +0.10″ | +0.8% |
| Sidewall height | 7.44″ | 6.50″ | −0.94″ | −12.6% |
| Circumference | 109.58″ | 103.67″ | −5.91″ | −5.4% |
| Revs per mile | 578.2 | 611.2 | +33.0 | +5.7% |
| Revs per km | 359.3 | 379.8 | +20.5 | +5.7% |
Speedometer: with 315/60R20 as the original, 33X12.50R20 makes an indicated 60 mph really about 56.8 mph, and the axle sits ~0.94″ lower.
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.