225/50R17 vs 255/40R18 tire size
255/40R18 vs 225/50R17, diameter
+0.7% taller
- Speedometer
- 59.6 mph
- At a true 60 mph
- Diameter
- 26.03 in
- Was 25.86 in
- Revs per mile
- 775
- Was 780
- 3% guideline
- Within
Car built for 225/50R17, now on 255/40R18.
225/50R17 and 255/40R18
| Measure | 225/50R17 | 255/40R18 | Difference |
|---|---|---|---|
| Width, mm | 225 | 255 | +30 |
| Sidewall, % of width | 50 | 40 | -10 |
| Rim, in | 17 | 18 | +1 |
| Section height, in | 4.43 | 4.02 | -0.41 |
| Diameter, in | 25.86 | 26.03 | +0.17 (+0.7%) |
| Circumference, in | 81.2 | 81.8 | +0.5 |
| Revs per mile | 780 | 775 | -5 (-0.7%) |
Fitting 255/40R18 instead of 225/50R17
Within the usual 3% diameter guideline.
- Needs 18 in wheels.
- 30 mm wider. Check rubbing at full lock.
Cars with 225/50R17
Cars with 255/40R18
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