275/40R19 vs 275/45R18
275/45R18 is a safe swap for 275/40R19 by the usual ±3% rule: the diameter differs by +0.30%.
Speedometer and odometer
With 275/45R18 on a car calibrated for 275/40R19, the speedometer reads 59.8 mph when you're really doing 60, and the odometer under-counts by 0.3%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.1 mph |
| 45 mph | 45.1 mph |
| 60 mph | 60.2 mph |
| 70 mph | 70.2 mph |
| 80 mph | 80.2 mph |
Other sizes close to 275/40R19
- 275/40R19 vs 245/45R19+0.07%
- 275/40R19 vs 245/40R19-3.42%
- 275/40R19 vs 255/50R19+4.98%
- 275/40R19 vs 235/40R19-4.55%
- 275/40R19 vs 255/40R19-2.28%
- 275/40R19 vs 225/55R18+0.30%
- 275/40R19 vs 245/40R20+0.20%
- 275/40R19 vs 255/45R19+1.35%
- 275/40R19 vs 275/35R19-3.91%
- 275/40R19 vs 225/55R19+3.91%
- 275/40R19 vs 275/35R20-0.30%
- 275/40R19 vs 225/45R19-2.49%
Questions
Can I replace 275/40R19 with 275/45R18?
275/45R18 is a safe swap for 275/40R19 by the usual ±3% rule: the diameter differs by +0.30%.
What's the difference between 275/40R19 and 275/45R18?
275/45R18 is 0.08" taller and 0 mm wider; the sidewall is +0.54". At an indicated 60 mph you'd actually be doing 60.2 mph.
Will 275/45R18 fit on 275/40R19 wheels?
No — 275/40R19 needs a 19" wheel and 275/45R18 a 18" wheel. This is a plus/minus-size swap that changes wheels too.