205/45R18 vs 225/40R18 tire size
225/40R18 vs 205/45R18, diameter
-0.7% shorter
- Speedometer
- 60.4 mph
- At a true 60 mph
- Diameter
- 25.09 in
- Was 25.26 in
- Revs per mile
- 804
- Was 798
- 3% guideline
- Within
Car built for 205/45R18, now on 225/40R18.
205/45R18 and 225/40R18
| Measure | 205/45R18 | 225/40R18 | Difference |
|---|---|---|---|
| Width, mm | 205 | 225 | +20 |
| Sidewall, % of width | 45 | 40 | -5 |
| Rim, in | 18 | 18 | 0 |
| Section height, in | 3.63 | 3.54 | -0.09 |
| Diameter, in | 25.26 | 25.09 | -0.18 (-0.7%) |
| Circumference, in | 79.4 | 78.8 | -0.6 |
| Revs per mile | 798 | 804 | +6 (+0.7%) |
Fitting 225/40R18 instead of 205/45R18
Within the usual 3% diameter guideline.
- 20 mm wider. Check rubbing at full lock.
Cars with 225/40R18
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