275/40R20 vs 285/35R21 tire size
285/35R21 vs 275/40R20, diameter
+0.7% taller
- Speedometer
- 59.6 mph
- At a true 60 mph
- Diameter
- 28.85 in
- Was 28.66 in
- Revs per mile
- 699
- Was 704
- 3% guideline
- Within
Car built for 275/40R20, now on 285/35R21.
275/40R20 and 285/35R21
| Measure | 275/40R20 | 285/35R21 | Difference |
|---|---|---|---|
| Width, mm | 275 | 285 | +10 |
| Sidewall, % of width | 40 | 35 | -5 |
| Rim, in | 20 | 21 | +1 |
| Section height, in | 4.33 | 3.93 | -0.40 |
| Diameter, in | 28.66 | 28.85 | +0.19 (+0.7%) |
| Circumference, in | 90.0 | 90.6 | +0.6 |
| Revs per mile | 704 | 699 | -5 (-0.7%) |
Fitting 285/35R21 instead of 275/40R20
Within the usual 3% diameter guideline.
- Needs 21 in wheels.
Cars with 275/40R20
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