275/40R18 vs 325/30R19
325/30R19 is a safe swap for 275/40R18 by the usual ±3% rule: the diameter differs by +0.06%.
Speedometer and odometer
With 325/30R19 on a car calibrated for 275/40R18, 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 275/40R18
- 275/40R18 vs 225/45R18-2.58%
- 275/40R18 vs 245/40R18-3.54%
- 275/40R18 vs 225/55R17+0.31%
- 275/40R18 vs 245/45R18+0.07%
- 275/40R18 vs 235/50R18+2.22%
- 275/40R18 vs 235/45R18-1.26%
- 275/40R18 vs 245/40R19+0.21%
- 275/40R18 vs 235/40R18-4.73%
- 275/40R18 vs 225/50R18+0.74%
- 275/40R18 vs 235/40R19-0.97%
- 275/40R18 vs 225/55R18+4.06%
- 275/40R18 vs 255/40R18-2.36%
Questions
Can I replace 275/40R18 with 325/30R19?
325/30R19 is a safe swap for 275/40R18 by the usual ±3% rule: the diameter differs by +0.06%.
What's the difference between 275/40R18 and 325/30R19?
325/30R19 is 0.02" taller and 50 mm wider; the sidewall is -0.49". At an indicated 60 mph you'd actually be doing 60.0 mph.
Will 325/30R19 fit on 275/40R18 wheels?
No — 275/40R18 needs a 18" wheel and 325/30R19 a 19" wheel. This is a plus/minus-size swap that changes wheels too.