285/45R20 vs 275/50R20
275/50R20 is a safe swap for 285/45R20 by the usual ±3% rule: the diameter differs by +2.42%.
Speedometer and odometer
With 275/50R20 on a car calibrated for 285/45R20, the speedometer reads 58.6 mph when you're really doing 60, and the odometer under-counts by 2.4%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.7 mph |
| 45 mph | 46.1 mph |
| 60 mph | 61.5 mph |
| 70 mph | 71.7 mph |
| 80 mph | 81.9 mph |
Other sizes close to 285/45R20
- 285/45R20 vs 245/45R20-4.71%
- 285/45R20 vs 255/45R20-3.53%
- 285/45R20 vs 255/50R20-0.20%
- 285/45R20 vs 275/40R20-4.77%
- 285/45R20 vs 265/50R20+1.11%
- 285/45R20 vs 245/50R20-1.50%
- 285/45R20 vs 275/45R20-1.18%
- 285/45R20 vs 255/55R20+3.14%
- 285/45R20 vs 235/55R20+0.26%
- 285/45R20 vs 265/45R20-2.35%
- 285/45R20 vs 255/55R19-0.18%
- 285/45R20 vs 315/35R20-4.71%
Questions
Can I replace 285/45R20 with 275/50R20?
275/50R20 is a safe swap for 285/45R20 by the usual ±3% rule: the diameter differs by +2.42%.
What's the difference between 285/45R20 and 275/50R20?
275/50R20 is 0.73" taller and 10 mm narrower; the sidewall is +0.36". At an indicated 60 mph you'd actually be doing 61.5 mph.
Will 275/50R20 fit on 285/45R20 wheels?
Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 275 mm tire and the fender clearance.