295/40R21 vs 275/50R21
275/50R21 is outside the ±3% rule as a replacement for 295/40R21: the diameter differs by +5.07%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 275/50R21 on a car calibrated for 295/40R21, the speedometer reads 57.1 mph when you're really doing 60, and the odometer under-counts by 5.1%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.5 mph |
| 45 mph | 47.3 mph |
| 60 mph | 63.0 mph |
| 70 mph | 73.5 mph |
| 80 mph | 84.1 mph |
Other sizes close to 295/40R21
- 295/40R21 vs 255/50R20-0.83%
- 295/40R21 vs 265/50R20+0.47%
- 295/40R21 vs 235/55R20-0.38%
- 295/40R21 vs 265/40R21-3.12%
- 295/40R21 vs 295/35R21-3.83%
- 295/40R21 vs 275/45R21+1.49%
- 295/40R21 vs 265/40R22+0.18%
- 295/40R21 vs 255/40R21-4.16%
- 295/40R21 vs 285/45R21+2.66%
- 295/40R21 vs 265/45R21+0.32%
- 295/40R21 vs 285/40R21-1.04%
- 295/40R21 vs 275/40R21-2.08%
Questions
Can I replace 295/40R21 with 275/50R21?
275/50R21 is outside the ±3% rule as a replacement for 295/40R21: the diameter differs by +5.07%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 295/40R21 and 275/50R21?
275/50R21 is 1.54" taller and 20 mm narrower; the sidewall is +0.77". At an indicated 60 mph you'd actually be doing 63.0 mph.
Will 275/50R21 fit on 295/40R21 wheels?
Both use a 21" rim, so the wheel diameter matches; check the wheel's width range for a 275 mm tire and the fender clearance.