255/40R20 vs 285/35R20 tire size
285/35R20 vs 255/40R20, diameter
-0.6% shorter
- Speedometer
- 60.4 mph
- At a true 60 mph
- Diameter
- 27.85 in
- Was 28.03 in
- Revs per mile
- 724
- Was 719
- 3% guideline
- Within
Car built for 255/40R20, now on 285/35R20.
255/40R20 and 285/35R20
| Measure | 255/40R20 | 285/35R20 | Difference |
|---|---|---|---|
| Width, mm | 255 | 285 | +30 |
| Sidewall, % of width | 40 | 35 | -5 |
| Rim, in | 20 | 20 | 0 |
| Section height, in | 4.02 | 3.93 | -0.09 |
| Diameter, in | 28.03 | 27.85 | -0.18 (-0.6%) |
| Circumference, in | 88.1 | 87.5 | -0.6 |
| Revs per mile | 719 | 724 | +5 (+0.6%) |
Fitting 285/35R20 instead of 255/40R20
Within the usual 3% diameter guideline.
- 30 mm wider. Check rubbing at full lock.
Cars with 255/40R20
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