265/50R20 vs 305/50R20
305/50R20 is outside the ±3% rule as a replacement for 265/50R20: the diameter differs by +5.17%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 305/50R20 on a car calibrated for 265/50R20, the speedometer reads 57.0 mph when you're really doing 60, and the odometer under-counts by 5.2%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.6 mph |
| 45 mph | 47.3 mph |
| 60 mph | 63.1 mph |
| 70 mph | 73.6 mph |
| 80 mph | 84.1 mph |
Other sizes close to 265/50R20
- 265/50R20 vs 275/55R20+4.85%
- 265/50R20 vs 255/45R20-4.59%
- 265/50R20 vs 255/50R20-1.29%
- 265/50R20 vs 245/50R20-2.59%
- 265/50R20 vs 275/45R20-2.26%
- 265/50R20 vs 255/55R20+2.01%
- 265/50R20 vs 235/55R20-0.84%
- 265/50R20 vs 265/45R20-3.43%
- 265/50R20 vs 275/50R20+1.29%
- 265/50R20 vs 295/40R20-3.75%
- 265/50R20 vs 285/50R20+2.59%
- 265/50R20 vs 295/40R21-0.47%
Questions
Can I replace 265/50R20 with 305/50R20?
305/50R20 is outside the ±3% rule as a replacement for 265/50R20: the diameter differs by +5.17%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 265/50R20 and 305/50R20?
305/50R20 is 1.57" taller and 40 mm wider; the sidewall is +0.79". At an indicated 60 mph you'd actually be doing 63.1 mph.
Will 305/50R20 fit on 265/50R20 wheels?
Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 305 mm tire and the fender clearance.