255/45R17 vs 255/40R18 tire size
255/40R18 vs 255/45R17, diameter
Same diameter
- Speedometer
- 60.0 mph
- At a true 60 mph
- Diameter
- 26.03 in
- Was 26.04 in
- Revs per mile
- 775
- Was 775
- 3% guideline
- Within
Car built for 255/45R17, now on 255/40R18.
255/45R17 and 255/40R18
| Measure | 255/45R17 | 255/40R18 | Difference |
|---|---|---|---|
| Width, mm | 255 | 255 | 0 |
| Sidewall, % of width | 45 | 40 | -5 |
| Rim, in | 17 | 18 | +1 |
| Section height, in | 4.52 | 4.02 | -0.50 |
| Diameter, in | 26.04 | 26.03 | 0 (-0.0%) |
| Circumference, in | 81.8 | 81.8 | -0.0 |
| Revs per mile | 775 | 775 | +0 (+0.0%) |
Fitting 255/40R18 instead of 255/45R17
Within the usual 3% diameter guideline.
- Needs 18 in wheels.
- Shorter sidewall: 0.5 in less.
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