215/50R17 vs 235/40R18 tire size
235/40R18 vs 215/50R17, diameter
-0.2% shorter
- Speedometer
- 60.1 mph
- At a true 60 mph
- Diameter
- 25.40 in
- Was 25.46 in
- Revs per mile
- 794
- Was 792
- 3% guideline
- Within
Car built for 215/50R17, now on 235/40R18.
215/50R17 and 235/40R18
| Measure | 215/50R17 | 235/40R18 | Difference |
|---|---|---|---|
| Width, mm | 215 | 235 | +20 |
| Sidewall, % of width | 50 | 40 | -10 |
| Rim, in | 17 | 18 | +1 |
| Section height, in | 4.23 | 3.70 | -0.53 |
| Diameter, in | 25.46 | 25.40 | -0.06 (-0.2%) |
| Circumference, in | 80.0 | 79.8 | -0.2 |
| Revs per mile | 792 | 794 | +2 (+0.2%) |
Fitting 235/40R18 instead of 215/50R17
Within the usual 3% diameter guideline.
- Needs 18 in wheels.
- 20 mm wider. Check rubbing at full lock.
- Shorter sidewall: 0.5 in less.
Cars with 215/50R17
Cars with 235/40R18
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