235/40R19 vs 315/30R19
315/30R19 is a safe swap for 235/40R19 by the usual ±3% rule: the diameter differs by +0.15%.
Speedometer and odometer
With 315/30R19 on a car calibrated for 235/40R19, the speedometer reads 59.9 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 | 45.1 mph |
| 60 mph | 60.1 mph |
| 70 mph | 70.1 mph |
| 80 mph | 80.1 mph |
Other sizes close to 235/40R19
- 235/40R19 vs 235/45R18-0.28%
- 235/40R19 vs 245/45R19+4.85%
- 235/40R19 vs 245/40R19+1.19%
- 235/40R19 vs 255/40R19+2.39%
- 235/40R19 vs 255/35R19-1.42%
- 235/40R19 vs 275/35R19+0.67%
- 235/40R19 vs 275/40R19+4.77%
- 235/40R19 vs 245/35R19-2.46%
- 235/40R19 vs 225/40R19-1.19%
- 235/40R19 vs 235/35R19-3.50%
- 235/40R19 vs 225/45R19+2.16%
- 235/40R19 vs 285/35R19+1.71%
Questions
Can I replace 235/40R19 with 315/30R19?
315/30R19 is a safe swap for 235/40R19 by the usual ±3% rule: the diameter differs by +0.15%.
What's the difference between 235/40R19 and 315/30R19?
315/30R19 is 0.04" taller and 80 mm wider; the sidewall is +0.02". At an indicated 60 mph you'd actually be doing 60.1 mph.
Will 315/30R19 fit on 235/40R19 wheels?
Both use a 19" rim, so the wheel diameter matches; check the wheel's width range for a 315 mm tire and the fender clearance.