315/30R18 vs 275/30R19
275/30R19 is a safe swap for 315/30R18 by the usual ±3% rule: the diameter differs by +0.22%.
Speedometer and odometer
With 275/30R19 on a car calibrated for 315/30R18, 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 | 30.1 mph |
| 45 mph | 45.1 mph |
| 60 mph | 60.1 mph |
| 70 mph | 70.2 mph |
| 80 mph | 80.2 mph |
Other sizes close to 315/30R18
- 315/30R18 vs 245/40R18+1.08%
- 315/30R18 vs 225/45R18+2.09%
- 315/30R18 vs 225/40R18-1.39%
- 315/30R18 vs 245/45R18+4.87%
- 315/30R18 vs 235/45R18+3.48%
- 315/30R18 vs 235/40R18-0.15%
- 315/30R18 vs 215/50R17+0.09%
- 315/30R18 vs 235/45R17-0.45%
- 315/30R18 vs 245/45R17+0.94%
- 315/30R18 vs 255/35R18-1.62%
- 315/30R18 vs 255/40R18+2.32%
- 315/30R18 vs 235/35R19+0.14%
Questions
Can I replace 315/30R18 with 275/30R19?
275/30R19 is a safe swap for 315/30R18 by the usual ±3% rule: the diameter differs by +0.22%.
What's the difference between 315/30R18 and 275/30R19?
275/30R19 is 0.06" taller and 40 mm narrower; the sidewall is -0.47". At an indicated 60 mph you'd actually be doing 60.1 mph.
Will 275/30R19 fit on 315/30R18 wheels?
No — 315/30R18 needs a 18" wheel and 275/30R19 a 19" wheel. This is a plus/minus-size swap that changes wheels too.