295/40R18 vs 245/55R18
245/55R18 is outside the ±3% rule as a replacement for 295/40R18: the diameter differs by +4.83%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 245/55R18 on a car calibrated for 295/40R18, the speedometer reads 57.2 mph when you're really doing 60, and the odometer under-counts by 4.8%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.4 mph |
| 45 mph | 47.2 mph |
| 60 mph | 62.9 mph |
| 70 mph | 73.4 mph |
| 80 mph | 83.9 mph |
Other sizes close to 295/40R18
- 295/40R18 vs 225/45R18-4.83%
- 295/40R18 vs 245/45R18-2.24%
- 295/40R18 vs 235/50R18-0.14%
- 295/40R18 vs 235/55R18+3.25%
- 295/40R18 vs 235/45R18-3.53%
- 295/40R18 vs 235/55R17-0.42%
- 295/40R18 vs 225/60R18+4.90%
- 295/40R18 vs 225/50R18-1.59%
- 295/40R18 vs 255/40R19-0.95%
- 295/40R18 vs 225/55R18+1.66%
- 295/40R18 vs 255/40R18-4.62%
- 295/40R18 vs 215/60R17-0.49%
Questions
Can I replace 295/40R18 with 245/55R18?
245/55R18 is outside the ±3% rule as a replacement for 295/40R18: the diameter differs by +4.83%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 295/40R18 and 245/55R18?
245/55R18 is 1.32" taller and 50 mm narrower; the sidewall is +0.66". At an indicated 60 mph you'd actually be doing 62.9 mph.
Will 245/55R18 fit on 295/40R18 wheels?
Both use a 18" rim, so the wheel diameter matches; check the wheel's width range for a 245 mm tire and the fender clearance.