245/40R18 vs 285/30R19
285/30R19 is a safe swap for 245/40R18 by the usual ±3% rule: the diameter differs by +0.06%.
Speedometer and odometer
With 285/30R19 on a car calibrated for 245/40R18, 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 245/40R18
- 245/40R18 vs 225/45R18+1.00%
- 245/40R18 vs 225/40R18-2.45%
- 245/40R18 vs 225/50R17+0.55%
- 245/40R18 vs 245/45R18+3.75%
- 245/40R18 vs 235/45R18+2.37%
- 245/40R18 vs 235/40R18-1.22%
- 245/40R18 vs 225/50R18+4.44%
- 245/40R18 vs 215/50R17-0.98%
- 245/40R18 vs 245/45R17-0.14%
- 245/40R18 vs 255/35R18-2.68%
- 245/40R18 vs 255/40R18+1.22%
- 245/40R18 vs 245/35R19+0.14%
Questions
Can I replace 245/40R18 with 285/30R19?
285/30R19 is a safe swap for 245/40R18 by the usual ±3% rule: the diameter differs by +0.06%.
What's the difference between 245/40R18 and 285/30R19?
285/30R19 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 285/30R19 fit on 245/40R18 wheels?
No — 245/40R18 needs a 18" wheel and 285/30R19 a 19" wheel. This is a plus/minus-size swap that changes wheels too.