325/30R19 vs 225/50R18
225/50R18 is a safe swap for 325/30R19 by the usual ±3% rule: the diameter differs by +0.68%.
Speedometer and odometer
With 225/50R18 on a car calibrated for 325/30R19, the speedometer reads 59.6 mph when you're really doing 60, and the odometer under-counts by 0.7%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.2 mph |
| 45 mph | 45.3 mph |
| 60 mph | 60.4 mph |
| 70 mph | 70.5 mph |
| 80 mph | 80.5 mph |
Other sizes close to 325/30R19
- 325/30R19 vs 245/45R18+0.01%
- 325/30R19 vs 245/45R19+3.76%
- 325/30R19 vs 245/40R19+0.15%
- 325/30R19 vs 235/40R19-1.03%
- 325/30R19 vs 255/40R19+1.33%
- 325/30R19 vs 255/35R19-2.44%
- 325/30R19 vs 275/35R19-0.37%
- 325/30R19 vs 275/40R19+3.69%
- 325/30R19 vs 245/35R20+0.28%
- 325/30R19 vs 245/35R19-3.47%
- 325/30R19 vs 225/40R19-2.21%
- 325/30R19 vs 235/35R19-4.50%
Questions
Can I replace 325/30R19 with 225/50R18?
225/50R18 is a safe swap for 325/30R19 by the usual ±3% rule: the diameter differs by +0.68%.
What's the difference between 325/30R19 and 225/50R18?
225/50R18 is 0.18" taller and 100 mm narrower; the sidewall is +0.59". At an indicated 60 mph you'd actually be doing 60.4 mph.
Will 225/50R18 fit on 325/30R19 wheels?
No — 325/30R19 needs a 19" wheel and 225/50R18 a 18" wheel. This is a plus/minus-size swap that changes wheels too.