255/70R17 vs 235/80R17
235/80R17 is a safe swap for 255/70R17 by the usual ±3% rule: the diameter differs by +2.41%.
Speedometer and odometer
With 235/80R17 on a car calibrated for 255/70R17, the speedometer reads 58.6 mph when you're really doing 60, and the odometer under-counts by 2.4%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.7 mph |
| 45 mph | 46.1 mph |
| 60 mph | 61.4 mph |
| 70 mph | 71.7 mph |
| 80 mph | 81.9 mph |
Other sizes close to 255/70R17
- 255/70R17 vs 265/70R17+1.77%
- 255/70R17 vs 245/70R17-1.77%
- 255/70R17 vs 245/65R17-4.88%
- 255/70R17 vs 245/75R17+1.33%
- 255/70R17 vs 265/65R17-1.58%
- 255/70R17 vs 255/65R18-0.01%
- 255/70R17 vs 255/65R17-3.23%
- 255/70R17 vs 255/75R17+3.23%
- 255/70R17 vs 235/75R17-0.57%
- 255/70R17 vs 275/70R17+3.55%
- 255/70R17 vs 235/70R17-3.55%
- 255/70R17 vs 275/60R18-0.20%
Questions
Can I replace 255/70R17 with 235/80R17?
235/80R17 is a safe swap for 255/70R17 by the usual ±3% rule: the diameter differs by +2.41%.
What's the difference between 255/70R17 and 235/80R17?
235/80R17 is 0.75" taller and 20 mm narrower; the sidewall is +0.37". At an indicated 60 mph you'd actually be doing 61.4 mph.
Will 235/80R17 fit on 255/70R17 wheels?
Both use a 17" rim, so the wheel diameter matches; check the wheel's width range for a 235 mm tire and the fender clearance.