245/40R19 vs 255/40R19
255/40R19 is taller than 245/40R19 by 1.18% — a diameter difference of 0.31″.
What changes between 245/40R19 and 255/40R19
Switching from 245/40R19 to 255/40R19 changes overall diameter by +1.18%, a taller tire by 0.31 inches. This lands inside the ±3% fitment safe zone, so most vehicles will accept the swap without rubbing, speedometer recalibration, or ABS/TPMS complications. Section width moves by +0.39″ (245mm → 255mm), which affects contact patch and fender-well clearance. Sidewall height shifts by +0.16″: a taller sidewall softens ride quality and adds off-road bump protection, with some loss of steering crispness. Revs per mile moves by -9, which translates directly to speedometer error — at an indicated 65 mph, actual speed becomes 65.8 mph. Both sizes share the same 19″ rim, so no wheel change is required — this is a pure tire-only swap.
| Spec | 245/40R19 | 255/40R19 |
|---|---|---|
| Overall diameter | 26.72″ | 27.03″ |
| Section width | 9.65″ (245 mm) | 10.04″ (255 mm) |
| Sidewall height | 3.86″ (40%) | 4.02″ (40%) |
| Rim diameter | 19″ | 19″ |
| Circumference | 83.93″ | 84.92″ |
| Revs per mile | 755 | 746 |
Interactive comparison
275/65R18 or "33" for inch aliases245/40R19
- Diameter
- 26.72″ / 678.6mm
- Section Width
- 9.65″
- Sidewall
- 3.86″ / 98mm
- Circumference
- 83.93″
- Revs/Mile
- 755
255/40R19
- Diameter
- 27.03″ / 686.6mm
- Section Width
- 10.04″
- Sidewall
- 4.02″ / 102mm
- Circumference
- 84.92″
- Revs/Mile
- 746
Speedometer & Diameter Impact
At an indicated 60 mph, your actual speed is 60.71 mph (97.7 km/h). Your speedometer reads 1.18% low versus actual speed.