255/60R18 vs 245/65R18
245/65R18 is taller than 255/60R18 by 1.64% — a diameter difference of 0.49″.
What changes between 255/60R18 and 245/65R18
Switching from 255/60R18 to 245/65R18 changes overall diameter by +1.64%, a taller tire by 0.49 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″ (255mm → 245mm), which affects contact patch and fender-well clearance. Sidewall height shifts by +0.25″: 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 66.1 mph. Both sizes share the same 18″ rim, so no wheel change is required — this is a pure tire-only swap.
| Spec | 255/60R18 | 245/65R18 |
|---|---|---|
| Overall diameter | 30.05″ | 30.54″ |
| Section width | 10.04″ (255 mm) | 9.65″ (245 mm) |
| Sidewall height | 6.02″ (60%) | 6.27″ (65%) |
| Rim diameter | 18″ | 18″ |
| Circumference | 94.4″ | 95.94″ |
| Revs per mile | 671 | 660 |
Interactive comparison
275/65R18 or "33" for inch aliases255/60R18
- Diameter
- 30.05″ / 763.2mm
- Section Width
- 10.04″
- Sidewall
- 6.02″ / 153mm
- Circumference
- 94.4″
- Revs/Mile
- 671
245/65R18
- Diameter
- 30.54″ / 775.7mm
- Section Width
- 9.65″
- Sidewall
- 6.27″ / 159.25mm
- Circumference
- 95.94″
- Revs/Mile
- 660
Speedometer & Diameter Impact
At an indicated 60 mph, your actual speed is 60.98 mph (98.14 km/h). Your speedometer reads 1.64% low versus actual speed.