ElpiAuto315/70R17 vs 33X12.50R17
33X12.50R17 is 1.36″ (35 mm) shorter than 315/70R17, a 4.0% difference in overall diameter — outside the ±3% band, so expect the speedometer to drift and check for rubbing before fitting.
| Measurement | 315/70R17 | 33X12.50R17 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 34.36″ | 33.00″ | −1.36″ | −4.0% |
| Section width | 12.40″ | 12.50″ | +0.10″ | +0.8% |
| Sidewall height | 8.68″ | 8.00″ | −0.68″ | −7.8% |
| Circumference | 107.95″ | 103.67″ | −4.28″ | −4.0% |
| Revs per mile | 586.9 | 611.2 | +24.2 | +4.1% |
| Revs per km | 364.7 | 379.8 | +15.1 | +4.1% |
Speedometer: with 315/70R17 as the original, 33X12.50R17 makes an indicated 60 mph really about 57.6 mph, and the axle sits ~0.68″ lower.
Reading this comparison
The overall diameter is what matters here: 315/70R17 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.