255/75R17 vs 305/65R17
305/65R17 is a safe swap for 255/75R17 by the usual ±3% rule: the diameter differs by +1.72%.
Speedometer and odometer
With 305/65R17 on a car calibrated for 255/75R17, the speedometer reads 59.0 mph when you're really doing 60, and the odometer under-counts by 1.7%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.5 mph |
| 45 mph | 45.8 mph |
| 60 mph | 61.0 mph |
| 70 mph | 71.2 mph |
| 80 mph | 81.4 mph |
Other sizes close to 255/75R17
- 255/75R17 vs 265/70R17-1.41%
- 255/75R17 vs 275/65R18+0.05%
- 255/75R17 vs 245/70R17-4.85%
- 255/75R17 vs 285/70R17+2.03%
- 255/75R17 vs 245/75R17-1.84%
- 255/75R17 vs 265/65R17-4.67%
- 255/75R17 vs 235/80R17-0.80%
- 255/75R17 vs 255/70R18-0.01%
- 255/75R17 vs 255/70R17-3.13%
- 255/75R17 vs 295/70R17+3.75%
- 255/75R17 vs 235/75R17-3.68%
- 255/75R17 vs 33x12.50R17+2.94%
Questions
Can I replace 255/75R17 with 305/65R17?
305/65R17 is a safe swap for 255/75R17 by the usual ±3% rule: the diameter differs by +1.72%.
What's the difference between 255/75R17 and 305/65R17?
305/65R17 is 0.55" taller and 50 mm wider; the sidewall is +0.28". At an indicated 60 mph you'd actually be doing 61.0 mph.
Will 305/65R17 fit on 255/75R17 wheels?
Both use a 17" rim, so the wheel diameter matches; check the wheel's width range for a 305 mm tire and the fender clearance.