255/60R20 vs 285/60R20
285/60R20 is outside the ±3% rule as a replacement for 255/60R20: the diameter differs by +4.42%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 285/60R20 on a car calibrated for 255/60R20, the speedometer reads 57.5 mph when you're really doing 60, and the odometer under-counts by 4.4%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.3 mph |
| 45 mph | 47.0 mph |
| 60 mph | 62.7 mph |
| 70 mph | 73.1 mph |
| 80 mph | 83.5 mph |
Other sizes close to 255/60R20
- 255/60R20 vs 275/55R20-0.43%
- 255/60R20 vs 275/60R20+2.95%
- 255/60R20 vs 255/55R20-3.13%
- 255/60R20 vs 265/60R20+1.47%
- 255/60R20 vs 305/55R20+3.62%
- 255/60R20 vs 285/55R20+0.92%
- 255/60R20 vs 275/50R20-3.81%
- 255/60R20 vs 33x12.50R20+2.97%
- 255/60R20 vs 295/55R20+2.27%
- 255/60R20 vs 285/50R20-2.58%
- 255/60R20 vs 245/60R20-1.47%
- 255/60R20 vs 305/50R20-0.12%
Questions
Can I replace 255/60R20 with 285/60R20?
285/60R20 is outside the ±3% rule as a replacement for 255/60R20: the diameter differs by +4.42%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 255/60R20 and 285/60R20?
285/60R20 is 1.42" taller and 30 mm wider; the sidewall is +0.71". At an indicated 60 mph you'd actually be doing 62.7 mph.
Will 285/60R20 fit on 255/60R20 wheels?
Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 285 mm tire and the fender clearance.