ElpiAuto315/60R20 vs 35X12.50R20
35X12.50R20 is 0.12″ (3 mm) taller than 315/60R20, a 0.3% difference in overall diameter — comfortably inside the ±3% band most fitment guides use, so it swaps straight across for gearing and the speedometer.
| Measurement | 315/60R20 | 35X12.50R20 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 34.88″ | 35.00″ | +0.12″ | +0.3% |
| Section width | 12.40″ | 12.50″ | +0.10″ | +0.8% |
| Sidewall height | 7.44″ | 7.50″ | +0.06″ | +0.8% |
| Circumference | 109.58″ | 109.96″ | +0.37″ | +0.3% |
| Revs per mile | 578.2 | 576.2 | −2.0 | −0.3% |
| Revs per km | 359.3 | 358.1 | −1.2 | −0.3% |
Speedometer: with 315/60R20 as the original, 35X12.50R20 makes an indicated 60 mph really about 60.2 mph, and the axle sits ~0.06″ higher.
Reading this comparison
The overall diameter is what matters here: 35X12.50R20 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.