275/30R20 vs 245/40R19
245/40R19 is a safe swap for 275/30R20 by the usual ±3% rule: the diameter differs by +0.83%.
Speedometer and odometer
With 245/40R19 on a car calibrated for 275/30R20, the speedometer reads 59.5 mph when you're really doing 60, and the odometer under-counts by 0.8%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.2 mph |
| 45 mph | 45.4 mph |
| 60 mph | 60.5 mph |
| 70 mph | 70.6 mph |
| 80 mph | 80.7 mph |
Other sizes close to 275/30R20
- 275/30R20 vs 235/40R19-0.36%
- 275/30R20 vs 245/40R20+4.61%
- 275/30R20 vs 275/35R19+0.31%
- 275/30R20 vs 245/35R20+0.97%
- 275/30R20 vs 255/35R20+2.01%
- 275/30R20 vs 275/35R20+4.09%
- 275/30R20 vs 265/35R19-0.73%
- 275/30R20 vs 285/30R20+0.89%
- 275/30R20 vs 265/35R20+3.05%
- 275/30R20 vs 235/35R20-0.07%
- 275/30R20 vs 295/30R20+1.78%
- 275/30R20 vs 305/30R20+2.67%
Questions
Can I replace 275/30R20 with 245/40R19?
245/40R19 is a safe swap for 275/30R20 by the usual ±3% rule: the diameter differs by +0.83%.
What's the difference between 275/30R20 and 245/40R19?
245/40R19 is 0.22" taller and 30 mm narrower; the sidewall is +0.61". At an indicated 60 mph you'd actually be doing 60.5 mph.
Will 245/40R19 fit on 275/30R20 wheels?
No — 275/30R20 needs a 20" wheel and 245/40R19 a 19" wheel. This is a plus/minus-size swap that changes wheels too.