275/40R21 vs 285/40R21 tire size
285/40R21 vs 275/40R21, diameter
+1.1% taller
- Speedometer
- 59.4 mph
- At a true 60 mph
- Diameter
- 29.98 in
- Was 29.66 in
- Revs per mile
- 673
- Was 680
- 3% guideline
- Within
Car built for 275/40R21, now on 285/40R21.
275/40R21 and 285/40R21
| Measure | 275/40R21 | 285/40R21 | Difference |
|---|---|---|---|
| Width, mm | 275 | 285 | +10 |
| Sidewall, % of width | 40 | 40 | 0 |
| Rim, in | 21 | 21 | 0 |
| Section height, in | 4.33 | 4.49 | +0.16 |
| Diameter, in | 29.66 | 29.98 | +0.31 (+1.1%) |
| Circumference, in | 93.2 | 94.2 | +1.0 |
| Revs per mile | 680 | 673 | -7 (-1.1%) |
Fitting 285/40R21 instead of 275/40R21
Within the usual 3% diameter guideline.
Cars with 275/40R21
Cars with 285/40R21
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