ElpiAuto235/75R17 vs 315/70R17
315/70R17 is 3.48″ (89 mm) taller than 235/75R17, a 11.3% difference in overall diameter — outside the ±3% band, so expect the speedometer to drift and check for rubbing before fitting.
The section widths are very different — these are not a like-for-like swap. Confirm wheel width and arch clearance separately.
| Measurement | 235/75R17 | 315/70R17 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 30.88″ | 34.36″ | +3.48″ | +11.3% |
| Section width | 9.25″ | 12.40″ | +3.15″ | +34.0% |
| Sidewall height | 6.94″ | 8.68″ | +1.74″ | +25.1% |
| Circumference | 97.01″ | 107.95″ | +10.95″ | +11.3% |
| Revs per mile | 653.2 | 586.9 | −66.2 | −10.1% |
| Revs per km | 405.9 | 364.7 | −41.2 | −10.1% |
Speedometer: with 235/75R17 as the original, 315/70R17 makes an indicated 60 mph really about 66.8 mph, and the axle sits ~1.74″ higher.
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.