ElpiAuto255/35R19 vs 245/40R19
245/40R19 is 0.69″ (17 mm) taller than 255/35R19, a 2.6% 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 | 255/35R19 | 245/40R19 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 26.03″ | 26.72″ | +0.69″ | +2.6% |
| Section width | 10.04″ | 9.65″ | −0.39″ | −3.9% |
| Sidewall height | 3.51″ | 3.86″ | +0.34″ | +9.8% |
| Circumference | 81.77″ | 83.93″ | +2.16″ | +2.6% |
| Revs per mile | 774.9 | 754.9 | −20.0 | −2.6% |
| Revs per km | 481.5 | 469.1 | −12.4 | −2.6% |
Speedometer: with 255/35R19 as the original, 245/40R19 makes an indicated 60 mph really about 61.6 mph, and the axle sits ~0.34″ higher.
Reading this comparison
The overall diameter is what matters here: 245/40R19 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.