265/45R21 vs 275/50R21
275/50R21 is outside the ±3% rule as a replacement for 265/45R21: the diameter differs by +4.73%, 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 265/45R21, the speedometer reads 57.3 mph when you're really doing 60, and the odometer under-counts by 4.7%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.4 mph |
| 45 mph | 47.1 mph |
| 60 mph | 62.8 mph |
| 70 mph | 73.3 mph |
| 80 mph | 83.8 mph |
Other sizes close to 265/45R21
- 265/45R21 vs 265/50R20+0.14%
- 265/45R21 vs 235/55R20-0.70%
- 265/45R21 vs 265/40R21-3.43%
- 265/45R21 vs 295/35R21-4.15%
- 265/45R21 vs 275/40R22+0.89%
- 265/45R21 vs 275/45R21+1.17%
- 265/45R21 vs 265/40R22-0.14%
- 265/45R21 vs 255/40R21-4.47%
- 265/45R21 vs 295/40R21-0.32%
- 265/45R21 vs 285/45R21+2.33%
- 265/45R21 vs 285/40R21-1.36%
- 265/45R21 vs 275/40R21-2.40%
Questions
Can I replace 265/45R21 with 275/50R21?
275/50R21 is outside the ±3% rule as a replacement for 265/45R21: the diameter differs by +4.73%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 265/45R21 and 275/50R21?
275/50R21 is 1.44" taller and 10 mm wider; the sidewall is +0.72". At an indicated 60 mph you'd actually be doing 62.8 mph.
Will 275/50R21 fit on 265/45R21 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.