255/70R17 vs 245/70R18 tire size
245/70R18 vs 255/70R17, diameter
+1.4% taller
- Speedometer
- 59.1 mph
- At a true 60 mph
- Diameter
- 31.50 in
- Was 31.06 in
- Revs per mile
- 640
- Was 649
- 3% guideline
- Within
Car built for 255/70R17, now on 245/70R18.
255/70R17 and 245/70R18
| Measure | 255/70R17 | 245/70R18 | Difference |
|---|---|---|---|
| Width, mm | 255 | 245 | -10 |
| Sidewall, % of width | 70 | 70 | 0 |
| Rim, in | 17 | 18 | +1 |
| Section height, in | 7.03 | 6.75 | -0.28 |
| Diameter, in | 31.06 | 31.50 | +0.45 (+1.4%) |
| Circumference, in | 97.6 | 99.0 | +1.4 |
| Revs per mile | 649 | 640 | -9 (-1.4%) |
Fitting 245/70R18 instead of 255/70R17
Within the usual 3% diameter guideline.
- Needs 18 in wheels.
Cars with 255/70R17
Cars with 245/70R18
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