275/45R21 vs 275/50R21
275/50R21 is outside the ±3% rule as a replacement for 275/45R21: the diameter differs by +3.52%, 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 275/45R21, the speedometer reads 58.0 mph when you're really doing 60, and the odometer under-counts by 3.5%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.1 mph |
| 45 mph | 46.6 mph |
| 60 mph | 62.1 mph |
| 70 mph | 72.5 mph |
| 80 mph | 82.8 mph |
Other sizes close to 275/45R21
- 275/45R21 vs 255/55R20+0.97%
- 275/45R21 vs 265/40R21-4.55%
- 275/45R21 vs 275/50R20+0.27%
- 275/45R21 vs 275/40R22-0.27%
- 275/45R21 vs 285/40R22+0.76%
- 275/45R21 vs 285/45R21+1.15%
- 275/45R21 vs 295/40R21-1.47%
- 275/45R21 vs 265/45R21-1.15%
- 275/45R21 vs 285/40R21-2.50%
- 275/45R21 vs 275/40R21-3.52%
- 275/45R21 vs 295/45R20-0.95%
- 275/45R21 vs 315/35R21-3.46%
Questions
Can I replace 275/45R21 with 275/50R21?
275/50R21 is outside the ±3% rule as a replacement for 275/45R21: the diameter differs by +3.52%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 275/45R21 and 275/50R21?
275/50R21 is 1.08" taller and 0 mm wider; the sidewall is +0.54". At an indicated 60 mph you'd actually be doing 62.1 mph.
Will 275/50R21 fit on 275/45R21 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.