245/40R19 vs 285/30R20
285/30R20 is a safe swap for 245/40R19 by the usual ±3% rule: the diameter differs by +0.06%.
Speedometer and odometer
With 285/30R20 on a car calibrated for 245/40R19, the speedometer reads 60.0 mph when you're really doing 60, and the odometer under-counts by 0.1%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.0 mph |
| 45 mph | 45.0 mph |
| 60 mph | 60.0 mph |
| 70 mph | 70.0 mph |
| 80 mph | 80.0 mph |
Other sizes close to 245/40R19
- 245/40R19 vs 245/45R18-0.13%
- 245/40R19 vs 245/45R19+3.61%
- 245/40R19 vs 225/50R18+0.53%
- 245/40R19 vs 235/40R19-1.18%
- 245/40R19 vs 255/40R19+1.18%
- 245/40R19 vs 255/35R19-2.58%
- 245/40R19 vs 255/45R19+4.94%
- 245/40R19 vs 275/35R19-0.52%
- 245/40R19 vs 275/40R19+3.54%
- 245/40R19 vs 245/35R20+0.13%
- 245/40R19 vs 245/35R19-3.61%
- 245/40R19 vs 225/40R19-2.36%
Questions
Can I replace 245/40R19 with 285/30R20?
285/30R20 is a safe swap for 245/40R19 by the usual ±3% rule: the diameter differs by +0.06%.
What's the difference between 245/40R19 and 285/30R20?
285/30R20 is 0.02" taller and 40 mm wider; the sidewall is -0.49". At an indicated 60 mph you'd actually be doing 60.0 mph.
Will 285/30R20 fit on 245/40R19 wheels?
No — 245/40R19 needs a 19" wheel and 285/30R20 a 20" wheel. This is a plus/minus-size swap that changes wheels too.