265/40R19 vs 265/45R18
265/45R18 is a safe swap for 265/40R19 by the usual ±3% rule: the diameter differs by +0.16%.
Speedometer and odometer
With 265/45R18 on a car calibrated for 265/40R19, the speedometer reads 59.9 mph when you're really doing 60, and the odometer under-counts by 0.2%.
| 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 265/40R19
- 265/40R19 vs 235/50R18-0.35%
- 265/40R19 vs 245/45R19+1.22%
- 265/40R19 vs 245/40R19-2.30%
- 265/40R19 vs 235/40R19-3.46%
- 265/40R19 vs 255/40R19-1.15%
- 265/40R19 vs 255/35R19-4.82%
- 265/40R19 vs 255/45R19+2.52%
- 265/40R19 vs 275/35R19-2.81%
- 265/40R19 vs 275/40R19+1.15%
- 265/40R19 vs 225/40R19-4.61%
- 265/40R19 vs 275/35R20+0.85%
- 265/40R19 vs 225/45R19-1.37%
Questions
Can I replace 265/40R19 with 265/45R18?
265/45R18 is a safe swap for 265/40R19 by the usual ±3% rule: the diameter differs by +0.16%.
What's the difference between 265/40R19 and 265/45R18?
265/45R18 is 0.04" taller and 0 mm wider; the sidewall is +0.52". At an indicated 60 mph you'd actually be doing 60.1 mph.
Will 265/45R18 fit on 265/40R19 wheels?
No — 265/40R19 needs a 19" wheel and 265/45R18 a 18" wheel. This is a plus/minus-size swap that changes wheels too.