245/60R18 vs 255/60R18
255/60R18 is taller than 245/60R18 by 1.60% — a diameter difference of 0.48″.
What changes between 245/60R18 and 255/60R18
Switching from 245/60R18 to 255/60R18 changes overall diameter by +1.60%, a taller tire by 0.48 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 +0.23″: a taller sidewall softens ride quality and adds off-road bump protection, with some loss of steering crispness. Revs per mile moves by -11, which translates directly to speedometer error — at an indicated 65 mph, actual speed becomes 66.0 mph. Both sizes share the same 18″ rim, so no wheel change is required — this is a pure tire-only swap.
| Spec | 245/60R18 | 255/60R18 |
|---|---|---|
| Overall diameter | 29.57″ | 30.05″ |
| Section width | 9.65″ (245 mm) | 10.04″ (255 mm) |
| Sidewall height | 5.79″ (60%) | 6.02″ (60%) |
| Rim diameter | 18″ | 18″ |
| Circumference | 92.91″ | 94.4″ |
| Revs per mile | 682 | 671 |
Interactive comparison
275/65R18 or "33" for inch aliases245/60R18
- Diameter
- 29.57″ / 751.2mm
- Section Width
- 9.65″
- Sidewall
- 5.79″ / 147mm
- Circumference
- 92.91″
- Revs/Mile
- 682
255/60R18
- Diameter
- 30.05″ / 763.2mm
- Section Width
- 10.04″
- Sidewall
- 6.02″ / 153mm
- Circumference
- 94.4″
- Revs/Mile
- 671
Speedometer & Diameter Impact
At an indicated 60 mph, your actual speed is 60.96 mph (98.1 km/h). Your speedometer reads 1.60% low versus actual speed.