345/30R19 vs 285/40R19
285/40R19 is outside the ±3% rule as a replacement for 345/30R19: the diameter differs by +3.05%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 285/40R19 on a car calibrated for 345/30R19, the speedometer reads 58.2 mph when you're really doing 60, and the odometer under-counts by 3.0%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.9 mph |
| 45 mph | 46.4 mph |
| 60 mph | 61.8 mph |
| 70 mph | 72.1 mph |
| 80 mph | 82.4 mph |
Other sizes close to 345/30R19
- 345/30R19 vs 235/50R18+0.38%
- 345/30R19 vs 245/45R19+1.96%
- 345/30R19 vs 245/40R19-1.60%
- 345/30R19 vs 235/40R19-2.76%
- 345/30R19 vs 255/40R19-0.44%
- 345/30R19 vs 255/35R19-4.13%
- 345/30R19 vs 255/45R19+3.26%
- 345/30R19 vs 275/35R19-2.10%
- 345/30R19 vs 275/40R19+1.89%
- 345/30R19 vs 255/35R20-0.45%
- 345/30R19 vs 225/40R19-3.92%
- 345/30R19 vs 225/45R19-0.65%
Questions
Can I replace 345/30R19 with 285/40R19?
285/40R19 is outside the ±3% rule as a replacement for 345/30R19: the diameter differs by +3.05%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 345/30R19 and 285/40R19?
285/40R19 is 0.83" taller and 60 mm narrower; the sidewall is +0.41". At an indicated 60 mph you'd actually be doing 61.8 mph.
Will 285/40R19 fit on 345/30R19 wheels?
Both use a 19" rim, so the wheel diameter matches; check the wheel's width range for a 285 mm tire and the fender clearance.