ElpiAuto315/60R20 vs 325/60R20
325/60R20 is 0.47″ (12 mm) taller than 315/60R20, a 1.4% 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 | 325/60R20 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 34.88″ | 35.35″ | +0.47″ | +1.4% |
| Section width | 12.40″ | 12.80″ | +0.39″ | +3.2% |
| Sidewall height | 7.44″ | 7.68″ | +0.24″ | +3.2% |
| Circumference | 109.58″ | 111.07″ | +1.48″ | +1.4% |
| Revs per mile | 578.2 | 570.5 | −7.7 | −1.3% |
| Revs per km | 359.3 | 354.5 | −4.8 | −1.3% |
Speedometer: with 315/60R20 as the original, 325/60R20 makes an indicated 60 mph really about 60.8 mph, and the axle sits ~0.24″ higher.
Reading this comparison
The overall diameter is what matters here: 325/60R20 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.