ElpiAuto245/75R17 vs 285/75R17
285/75R17 is 2.36″ (60 mm) taller than 245/75R17, a 7.5% difference in overall diameter — outside the ±3% band, so expect the speedometer to drift and check for rubbing before fitting.
| Measurement | 245/75R17 | 285/75R17 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 31.47″ | 33.83″ | +2.36″ | +7.5% |
| Section width | 9.65″ | 11.22″ | +1.57″ | +16.3% |
| Sidewall height | 7.23″ | 8.42″ | +1.18″ | +16.3% |
| Circumference | 98.86″ | 106.28″ | +7.42″ | +7.5% |
| Revs per mile | 640.9 | 596.1 | −44.8 | −7.0% |
| Revs per km | 398.2 | 370.4 | −27.8 | −7.0% |
Speedometer: with 245/75R17 as the original, 285/75R17 makes an indicated 60 mph really about 64.5 mph, and the axle sits ~1.18″ higher.
Reading this comparison
The overall diameter is what matters here: 285/75R17 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.