275/50R20 vs 285/55R20
285/55R20 is outside the ±3% rule as a replacement for 275/50R20: the diameter differs by +4.92%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 285/55R20 on a car calibrated for 275/50R20, the speedometer reads 57.2 mph when you're really doing 60, and the odometer under-counts by 4.9%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.5 mph |
| 45 mph | 47.2 mph |
| 60 mph | 63.0 mph |
| 70 mph | 73.4 mph |
| 80 mph | 83.9 mph |
Other sizes close to 275/50R20
- 275/50R20 vs 275/55R20+3.51%
- 275/50R20 vs 255/50R20-2.55%
- 275/50R20 vs 265/50R20-1.28%
- 275/50R20 vs 245/50R20-3.83%
- 275/50R20 vs 275/45R20-3.51%
- 275/50R20 vs 255/55R20+0.70%
- 275/50R20 vs 235/55R20-2.11%
- 275/50R20 vs 265/45R20-4.66%
- 275/50R20 vs 255/60R19+0.72%
- 275/50R20 vs 275/45R21-0.27%
- 275/50R20 vs 295/40R20-4.98%
- 275/50R20 vs 285/50R20+1.28%
Questions
Can I replace 275/50R20 with 285/55R20?
285/55R20 is outside the ±3% rule as a replacement for 275/50R20: the diameter differs by +4.92%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 275/50R20 and 285/55R20?
285/55R20 is 1.52" taller and 10 mm wider; the sidewall is +0.76". At an indicated 60 mph you'd actually be doing 63.0 mph.
Will 285/55R20 fit on 275/50R20 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.