225/50R17 vs 245/40R18 tire size
245/40R18 vs 225/50R17, diameter
-0.5% shorter
- Speedometer
- 60.3 mph
- At a true 60 mph
- Diameter
- 25.72 in
- Was 25.86 in
- Revs per mile
- 784
- Was 780
- 3% guideline
- Within
Car built for 225/50R17, now on 245/40R18.
225/50R17 and 245/40R18
| Measure | 225/50R17 | 245/40R18 | Difference |
|---|---|---|---|
| Width, mm | 225 | 245 | +20 |
| Sidewall, % of width | 50 | 40 | -10 |
| Rim, in | 17 | 18 | +1 |
| Section height, in | 4.43 | 3.86 | -0.57 |
| Diameter, in | 25.86 | 25.72 | -0.14 (-0.5%) |
| Circumference, in | 81.2 | 80.8 | -0.4 |
| Revs per mile | 780 | 784 | +4 (+0.6%) |
Fitting 245/40R18 instead of 225/50R17
Within the usual 3% diameter guideline.
- Needs 18 in wheels.
- 20 mm wider. Check rubbing at full lock.
- Shorter sidewall: 0.6 in less.
Cars with 225/50R17
Cars with 245/40R18
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