285/40R19 vs 255/45R19
255/45R19 is a safe swap for 285/40R19 by the usual ±3% rule: the diameter differs by +0.21%.
Speedometer and odometer
With 255/45R19 on a car calibrated for 285/40R19, the speedometer reads 59.9 mph when you're really doing 60, and the odometer under-counts by 0.2%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.1 mph |
| 45 mph | 45.1 mph |
| 60 mph | 60.1 mph |
| 70 mph | 70.1 mph |
| 80 mph | 80.2 mph |
Other sizes close to 285/40R19
- 285/40R19 vs 235/55R19+4.29%
- 285/40R19 vs 235/55R18+0.72%
- 285/40R19 vs 245/45R19-1.06%
- 285/40R19 vs 245/40R19-4.50%
- 285/40R19 vs 255/50R19+3.80%
- 285/40R19 vs 255/40R19-3.38%
- 285/40R19 vs 225/55R18-0.83%
- 285/40R19 vs 245/40R20-0.93%
- 285/40R19 vs 275/35R19-5.00%
- 285/40R19 vs 225/55R19+2.74%
- 285/40R19 vs 275/40R19-1.13%
- 285/40R19 vs 255/40R20+0.20%
Questions
Can I replace 285/40R19 with 255/45R19?
255/45R19 is a safe swap for 285/40R19 by the usual ±3% rule: the diameter differs by +0.21%.
What's the difference between 285/40R19 and 255/45R19?
255/45R19 is 0.06" taller and 30 mm narrower; the sidewall is +0.03". At an indicated 60 mph you'd actually be doing 60.1 mph.
Will 255/45R19 fit on 285/40R19 wheels?
Both use a 19" rim, so the wheel diameter matches; check the wheel's width range for a 255 mm tire and the fender clearance.