ElpiAuto245/35R19 vs 255/40R19
255/40R19 is 1.28″ (33 mm) taller than 245/35R19, a 5.0% difference in overall diameter — outside the ±3% band, so expect the speedometer to drift and check for rubbing before fitting.
| Measurement | 245/35R19 | 255/40R19 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 25.75″ | 27.03″ | +1.28″ | +5.0% |
| Section width | 9.65″ | 10.04″ | +0.39″ | +4.1% |
| Sidewall height | 3.38″ | 4.02″ | +0.64″ | +19.0% |
| Circumference | 80.90″ | 84.92″ | +4.02″ | +5.0% |
| Revs per mile | 783.2 | 746.1 | −37.1 | −4.7% |
| Revs per km | 486.6 | 463.6 | −23.0 | −4.7% |
Speedometer: with 245/35R19 as the original, 255/40R19 makes an indicated 60 mph really about 63.0 mph, and the axle sits ~0.64″ higher.
Reading this comparison
The overall diameter is what matters here: 255/40R19 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.