225/45R17 vs 225/40R18 tire size
225/40R18 vs 225/45R17, diameter
+0.5% taller
- Speedometer
- 59.7 mph
- At a true 60 mph
- Diameter
- 25.09 in
- Was 24.97 in
- Revs per mile
- 804
- Was 808
- 3% guideline
- Within
Car built for 225/45R17, now on 225/40R18.
225/45R17 and 225/40R18
| Measure | 225/45R17 | 225/40R18 | Difference |
|---|---|---|---|
| Width, mm | 225 | 225 | 0 |
| Sidewall, % of width | 45 | 40 | -5 |
| Rim, in | 17 | 18 | +1 |
| Section height, in | 3.99 | 3.54 | -0.44 |
| Diameter, in | 24.97 | 25.09 | +0.11 (+0.5%) |
| Circumference, in | 78.5 | 78.8 | +0.4 |
| Revs per mile | 808 | 804 | -4 (-0.5%) |
Fitting 225/40R18 instead of 225/45R17
Within the usual 3% diameter guideline.
- Needs 18 in wheels.
Cars with 225/45R17
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