275/60R20 vs 305/55R20
305/55R20 is a safe swap for 275/60R20 by the usual ±3% rule: the diameter differs by +0.66%.
Speedometer and odometer
With 305/55R20 on a car calibrated for 275/60R20, the speedometer reads 59.6 mph when you're really doing 60, and the odometer under-counts by 0.7%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.2 mph |
| 45 mph | 45.3 mph |
| 60 mph | 60.4 mph |
| 70 mph | 70.5 mph |
| 80 mph | 80.5 mph |
Other sizes close to 275/60R20
- 275/60R20 vs 275/55R20-3.28%
- 275/60R20 vs 275/65R20+3.28%
- 275/60R20 vs 265/60R20-1.43%
- 275/60R20 vs 285/55R20-1.97%
- 275/60R20 vs 285/60R20+1.43%
- 275/60R20 vs 33x12.50R20+0.02%
- 275/60R20 vs 295/60R20+2.86%
- 275/60R20 vs 295/55R20-0.66%
- 275/60R20 vs 285/65R20+4.83%
- 275/60R20 vs 245/60R20-4.30%
- 275/60R20 vs 305/50R20-2.98%
- 275/60R20 vs 255/60R20-2.86%
Questions
Can I replace 275/60R20 with 305/55R20?
305/55R20 is a safe swap for 275/60R20 by the usual ±3% rule: the diameter differs by +0.66%.
What's the difference between 275/60R20 and 305/55R20?
305/55R20 is 0.22" taller and 30 mm wider; the sidewall is +0.11". At an indicated 60 mph you'd actually be doing 60.4 mph.
Will 305/55R20 fit on 275/60R20 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.