ElpiAuto225/50R17 vs 245/45R17
245/45R17 is 0.18″ (4 mm) shorter than 225/50R17, a 0.7% difference in overall diameter — comfortably inside the ±3% band most fitment guides use, so it swaps straight across for gearing and the speedometer.
| Measurement | 225/50R17 | 245/45R17 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 25.86″ | 25.68″ | −0.18″ | −0.7% |
| Section width | 8.86″ | 9.65″ | +0.79″ | +8.9% |
| Sidewall height | 4.43″ | 4.34″ | −0.09″ | −2.0% |
| Circumference | 81.24″ | 80.68″ | −0.56″ | −0.7% |
| Revs per mile | 779.9 | 785.3 | +5.4 | +0.7% |
| Revs per km | 484.6 | 488.0 | +3.3 | +0.7% |
Speedometer: with 225/50R17 as the original, 245/45R17 makes an indicated 60 mph really about 59.6 mph, and the axle sits ~0.09″ lower.
Reading this comparison
The overall diameter is what matters here: 225/50R17 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.