245/70R17 vs 235/80R17
235/80R17 is outside the ±3% rule as a replacement for 245/70R17: the diameter differs by +4.26%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 235/80R17 on a car calibrated for 245/70R17, the speedometer reads 57.5 mph when you're really doing 60, and the odometer under-counts by 4.3%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.3 mph |
| 45 mph | 46.9 mph |
| 60 mph | 62.6 mph |
| 70 mph | 73.0 mph |
| 80 mph | 83.4 mph |
Other sizes close to 245/70R17
- 245/70R17 vs 265/70R17+3.61%
- 245/70R17 vs 235/65R17-4.84%
- 245/70R17 vs 265/60R18+0.05%
- 245/70R17 vs 245/65R17-3.16%
- 245/70R17 vs 245/75R16-0.12%
- 245/70R17 vs 245/75R17+3.16%
- 245/70R17 vs 265/65R17+0.19%
- 245/70R17 vs 265/70R16+0.34%
- 245/70R17 vs 255/65R17-1.48%
- 245/70R17 vs 215/85R16-0.37%
- 245/70R17 vs 255/70R17+1.81%
- 245/70R17 vs 235/75R17+1.23%
Questions
Can I replace 245/70R17 with 235/80R17?
235/80R17 is outside the ±3% rule as a replacement for 245/70R17: the diameter differs by +4.26%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 245/70R17 and 235/80R17?
235/80R17 is 1.30" taller and 10 mm narrower; the sidewall is +0.65". At an indicated 60 mph you'd actually be doing 62.6 mph.
Will 235/80R17 fit on 245/70R17 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.