175/55R20 vs 245/40R20 tire size
245/40R20 vs 175/55R20, diameter
+0.5% taller
- Speedometer
- 59.7 mph
- At a true 60 mph
- Diameter
- 27.72 in
- Was 27.58 in
- Revs per mile
- 728
- Was 731
- 3% guideline
- Within
Car built for 175/55R20, now on 245/40R20.
175/55R20 and 245/40R20
| Measure | 175/55R20 | 245/40R20 | Difference |
|---|---|---|---|
| Width, mm | 175 | 245 | +70 |
| Sidewall, % of width | 55 | 40 | -15 |
| Rim, in | 20 | 20 | 0 |
| Section height, in | 3.79 | 3.86 | +0.07 |
| Diameter, in | 27.58 | 27.72 | +0.14 (+0.5%) |
| Circumference, in | 86.6 | 87.1 | +0.4 |
| Revs per mile | 731 | 728 | -4 (-0.5%) |
Fitting 245/40R20 instead of 175/55R20
Within the usual 3% diameter guideline.
- 70 mm wider. Check rubbing at full lock.
Cars with 175/55R20
Cars with 245/40R20
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