275/60R18 vs 255/70R18
255/70R18 is outside the ±3% rule as a replacement for 275/60R18: the diameter differs by +3.43%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 255/70R18 on a car calibrated for 275/60R18, the speedometer reads 58.0 mph when you're really doing 60, and the odometer under-counts by 3.4%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.0 mph |
| 45 mph | 46.5 mph |
| 60 mph | 62.1 mph |
| 70 mph | 72.4 mph |
| 80 mph | 82.7 mph |
Other sizes close to 275/60R18
- 275/60R18 vs 275/65R18+3.49%
- 275/60R18 vs 265/60R18-1.52%
- 275/60R18 vs 245/60R18-4.57%
- 275/60R18 vs 265/65R18+1.84%
- 275/60R18 vs 235/65R18-3.11%
- 275/60R18 vs 255/65R18+0.19%
- 275/60R18 vs 255/60R19+0.18%
- 275/60R18 vs 255/70R17+0.20%
- 275/60R18 vs 255/60R18-3.05%
- 275/60R18 vs 235/75R17-0.37%
- 275/60R18 vs 285/60R18+1.52%
- 275/60R18 vs 275/55R19-0.27%
Questions
Can I replace 275/60R18 with 255/70R18?
255/70R18 is outside the ±3% rule as a replacement for 275/60R18: the diameter differs by +3.43%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 275/60R18 and 255/70R18?
255/70R18 is 1.06" taller and 20 mm narrower; the sidewall is +0.53". At an indicated 60 mph you'd actually be doing 62.1 mph.
Will 255/70R18 fit on 275/60R18 wheels?
Both use a 18" rim, so the wheel diameter matches; check the wheel's width range for a 255 mm tire and the fender clearance.