275/45R20 vs 285/50R20
285/50R20 is outside the ±3% rule as a replacement for 275/45R20: the diameter differs by +4.96%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 285/50R20 on a car calibrated for 275/45R20, the speedometer reads 57.2 mph when you're really doing 60, and the odometer under-counts by 5.0%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.5 mph |
| 45 mph | 47.2 mph |
| 60 mph | 63.0 mph |
| 70 mph | 73.5 mph |
| 80 mph | 84.0 mph |
Other sizes close to 275/45R20
- 275/45R20 vs 245/45R20-3.57%
- 275/45R20 vs 255/45R20-2.38%
- 275/45R20 vs 255/50R20+0.99%
- 275/45R20 vs 275/40R20-3.64%
- 275/45R20 vs 265/50R20+2.32%
- 275/45R20 vs 245/50R20-0.33%
- 275/45R20 vs 255/55R20+4.37%
- 275/45R20 vs 235/55R20+1.46%
- 275/45R20 vs 245/55R19-0.45%
- 275/45R20 vs 265/45R20-1.19%
- 275/45R20 vs 315/35R20-3.57%
- 275/45R20 vs 275/50R20+3.64%
Questions
Can I replace 275/45R20 with 285/50R20?
285/50R20 is outside the ±3% rule as a replacement for 275/45R20: the diameter differs by +4.96%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 275/45R20 and 285/50R20?
285/50R20 is 1.48" taller and 10 mm wider; the sidewall is +0.74". At an indicated 60 mph you'd actually be doing 63.0 mph.
Will 285/50R20 fit on 275/45R20 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.