235/50R18 vs 255/45R18 tire size
255/45R18 vs 235/50R18, diameter
-0.8% shorter
- Speedometer
- 60.5 mph
- At a true 60 mph
- Diameter
- 27.04 in
- Was 27.25 in
- Revs per mile
- 746
- Was 740
- 3% guideline
- Within
Car built for 235/50R18, now on 255/45R18.
235/50R18 and 255/45R18
| Measure | 235/50R18 | 255/45R18 | Difference |
|---|---|---|---|
| Width, mm | 235 | 255 | +20 |
| Sidewall, % of width | 50 | 45 | -5 |
| Rim, in | 18 | 18 | 0 |
| Section height, in | 4.63 | 4.52 | -0.11 |
| Diameter, in | 27.25 | 27.04 | -0.22 (-0.8%) |
| Circumference, in | 85.6 | 84.9 | -0.7 |
| Revs per mile | 740 | 746 | +6 (+0.8%) |
Fitting 255/45R18 instead of 235/50R18
Within the usual 3% diameter guideline.
- 20 mm wider. Check rubbing at full lock.
Cars with 235/50R18
Cars with 255/45R18
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