275/45R19 vs 285/40R20
285/40R20 is a safe swap for 275/45R19 by the usual ±3% rule: the diameter differs by +0.81%.
Speedometer and odometer
With 285/40R20 on a car calibrated for 275/45R19, the speedometer reads 59.5 mph when you're really doing 60, and the odometer under-counts by 0.8%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.2 mph |
| 45 mph | 45.4 mph |
| 60 mph | 60.5 mph |
| 70 mph | 70.6 mph |
| 80 mph | 80.6 mph |
Other sizes close to 275/45R19
- 275/45R19 vs 235/55R19+1.51%
- 275/45R19 vs 245/45R19-3.70%
- 275/45R19 vs 225/60R18-0.40%
- 275/45R19 vs 245/45R20-0.22%
- 275/45R19 vs 255/50R19+1.03%
- 275/45R19 vs 275/40R20-0.29%
- 275/45R19 vs 255/45R19-2.47%
- 275/45R19 vs 225/55R190.00%
- 275/45R19 vs 275/40R19-3.77%
- 275/45R19 vs 235/50R19-1.71%
- 275/45R19 vs 245/55R19+3.01%
- 275/45R19 vs 255/55R19+4.52%
Questions
Can I replace 275/45R19 with 285/40R20?
285/40R20 is a safe swap for 275/45R19 by the usual ±3% rule: the diameter differs by +0.81%.
What's the difference between 275/45R19 and 285/40R20?
285/40R20 is 0.23" taller and 10 mm wider; the sidewall is -0.38". At an indicated 60 mph you'd actually be doing 60.5 mph.
Will 285/40R20 fit on 275/45R19 wheels?
No — 275/45R19 needs a 19" wheel and 285/40R20 a 20" wheel. This is a plus/minus-size swap that changes wheels too.