255/75R17 vs 245/75R18 tire size
245/75R18 vs 255/75R17, diameter
+1.3% taller
- Speedometer
- 59.2 mph
- At a true 60 mph
- Diameter
- 32.47 in
- Was 32.06 in
- Revs per mile
- 621
- Was 629
- 3% guideline
- Within
Car built for 255/75R17, now on 245/75R18.
255/75R17 and 245/75R18
| Measure | 255/75R17 | 245/75R18 | Difference |
|---|---|---|---|
| Width, mm | 255 | 245 | -10 |
| Sidewall, % of width | 75 | 75 | 0 |
| Rim, in | 17 | 18 | +1 |
| Section height, in | 7.53 | 7.23 | -0.30 |
| Diameter, in | 32.06 | 32.47 | +0.41 (+1.3%) |
| Circumference, in | 100.7 | 102.0 | +1.3 |
| Revs per mile | 629 | 621 | -8 (-1.3%) |
Fitting 245/75R18 instead of 255/75R17
Within the usual 3% diameter guideline.
- Needs 18 in wheels.
Cars with 255/75R17
Cars with 245/75R18
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