ElpiAuto225/45R17 vs 245/45R17
245/45R17 is 0.71″ (18 mm) taller than 225/45R17, a 2.8% difference in overall diameter — right at the edge of the ±3% band — fine on most cars, but check clearance at full lock and full suspension compression.
| Measurement | 225/45R17 | 245/45R17 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 24.97″ | 25.68″ | +0.71″ | +2.8% |
| Section width | 8.86″ | 9.65″ | +0.79″ | +8.9% |
| Sidewall height | 3.99″ | 4.34″ | +0.35″ | +8.9% |
| Circumference | 78.45″ | 80.68″ | +2.23″ | +2.8% |
| Revs per mile | 807.6 | 785.3 | −22.3 | −2.8% |
| Revs per km | 501.8 | 488.0 | −13.8 | −2.8% |
Speedometer: with 225/45R17 as the original, 245/45R17 makes an indicated 60 mph really about 61.7 mph, and the axle sits ~0.35″ higher.
Reading this comparison
The overall diameter is what matters here: 245/45R17 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.