ElpiAuto245/75R17 vs 37X12.50R17
37X12.50R17 is 5.53″ (141 mm) taller than 245/75R17, a 17.6% 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 | 245/75R17 | 37X12.50R17 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 31.47″ | 37.00″ | +5.53″ | +17.6% |
| Section width | 9.65″ | 12.50″ | +2.85″ | +29.6% |
| Sidewall height | 7.23″ | 10.00″ | +2.77″ | +38.2% |
| Circumference | 98.86″ | 116.24″ | +17.38″ | +17.6% |
| Revs per mile | 640.9 | 545.1 | −95.8 | −14.9% |
| Revs per km | 398.2 | 338.7 | −59.5 | −14.9% |
Speedometer: with 245/75R17 as the original, 37X12.50R17 makes an indicated 60 mph really about 70.5 mph, and the axle sits ~2.77″ higher.
Reading this comparison
The overall diameter is what matters here: 37X12.50R17 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.