235/70R17 vs 255/70R17
255/70R17 is outside the ±3% rule as a replacement for 235/70R17: the diameter differs by +3.68%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 255/70R17 on a car calibrated for 235/70R17, the speedometer reads 57.9 mph when you're really doing 60, and the odometer under-counts by 3.7%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.1 mph |
| 45 mph | 46.7 mph |
| 60 mph | 62.2 mph |
| 70 mph | 72.6 mph |
| 80 mph | 82.9 mph |
Other sizes close to 235/70R17
- 235/70R17 vs 225/65R17-4.80%
- 235/70R17 vs 235/65R17-3.09%
- 235/70R17 vs 245/65R17-1.38%
- 235/70R17 vs 245/70R17+1.84%
- 235/70R17 vs 235/65R18+0.25%
- 235/70R17 vs 265/65R17+2.04%
- 235/70R17 vs 255/65R17+0.33%
- 235/70R17 vs 255/70R16+0.34%
- 235/70R17 vs 255/60R18+0.32%
- 235/70R17 vs 235/75R17+3.09%
- 235/70R17 vs 235/75R16-0.25%
- 235/70R17 vs 255/60R17-3.02%
Questions
Can I replace 235/70R17 with 255/70R17?
255/70R17 is outside the ±3% rule as a replacement for 235/70R17: the diameter differs by +3.68%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 235/70R17 and 255/70R17?
255/70R17 is 1.10" taller and 20 mm wider; the sidewall is +0.55". At an indicated 60 mph you'd actually be doing 62.2 mph.
Will 255/70R17 fit on 235/70R17 wheels?
Both use a 17" rim, so the wheel diameter matches; check the wheel's width range for a 255 mm tire and the fender clearance.