235/80R17 vs 255/70R18 tire size
255/70R18 vs 235/80R17, diameter
+0.8% taller
- Speedometer
- 59.5 mph
- At a true 60 mph
- Diameter
- 32.06 in
- Was 31.80 in
- Revs per mile
- 629
- Was 634
- 3% guideline
- Within
Car built for 235/80R17, now on 255/70R18.
235/80R17 and 255/70R18
| Measure | 235/80R17 | 255/70R18 | Difference |
|---|---|---|---|
| Width, mm | 235 | 255 | +20 |
| Sidewall, % of width | 80 | 70 | -10 |
| Rim, in | 17 | 18 | +1 |
| Section height, in | 7.40 | 7.03 | -0.37 |
| Diameter, in | 31.80 | 32.06 | +0.25 (+0.8%) |
| Circumference, in | 99.9 | 100.7 | +0.8 |
| Revs per mile | 634 | 629 | -5 (-0.8%) |
Fitting 255/70R18 instead of 235/80R17
Within the usual 3% diameter guideline.
- Needs 18 in wheels.
- 20 mm wider. Check rubbing at full lock.
Cars with 255/70R18
What this cannot tell you
Diameter within 3% is a common shop guideline, not a maker spec.
Load index, offset and clearance are not in this data.
- Two or more sources agree
- One source
- Model-level or estimate
- Sources differ