245/45R17 vs 245/40R18 tire size
245/40R18 vs 245/45R17, diameter
+0.1% taller
- Speedometer
- 59.9 mph
- At a true 60 mph
- Diameter
- 25.72 in
- Was 25.68 in
- Revs per mile
- 784
- Was 785
- 3% guideline
- Within
Car built for 245/45R17, now on 245/40R18.
245/45R17 and 245/40R18
| Measure | 245/45R17 | 245/40R18 | Difference |
|---|---|---|---|
| Width, mm | 245 | 245 | 0 |
| Sidewall, % of width | 45 | 40 | -5 |
| Rim, in | 17 | 18 | +1 |
| Section height, in | 4.34 | 3.86 | -0.48 |
| Diameter, in | 25.68 | 25.72 | +0.04 (+0.1%) |
| Circumference, in | 80.7 | 80.8 | +0.1 |
| Revs per mile | 785 | 784 | -1 (-0.1%) |
Fitting 245/40R18 instead of 245/45R17
Within the usual 3% diameter guideline.
- Needs 18 in wheels.
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