ElpiAuto235/45R17 vs 235/55R17
235/55R17 is 1.85″ (47 mm) taller than 235/45R17, a 7.3% difference in overall diameter — outside the ±3% band, so expect the speedometer to drift and check for rubbing before fitting.
| Measurement | 235/45R17 | 235/55R17 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 25.33″ | 27.18″ | +1.85″ | +7.3% |
| Section width | 9.25″ | 9.25″ | — | |
| Sidewall height | 4.16″ | 5.09″ | +0.93″ | +22.2% |
| Circumference | 79.57″ | 85.38″ | +5.81″ | +7.3% |
| Revs per mile | 796.3 | 742.1 | −54.2 | −6.8% |
| Revs per km | 494.8 | 461.1 | −33.7 | −6.8% |
Speedometer: with 235/45R17 as the original, 235/55R17 makes an indicated 60 mph really about 64.4 mph, and the axle sits ~0.93″ higher.
Reading this comparison
The overall diameter is what matters here: 235/55R17 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.