285/40R20 vs 225/45R21 tire size
225/45R21 vs 285/40R20, diameter
Same diameter
- Speedometer
- 60.0 mph
- At a true 60 mph
- Diameter
- 28.97 in
- Was 28.98 in
- Revs per mile
- 696
- Was 696
- 3% guideline
- Within
Car built for 285/40R20, now on 225/45R21.
285/40R20 and 225/45R21
| Measure | 285/40R20 | 225/45R21 | Difference |
|---|---|---|---|
| Width, mm | 285 | 225 | -60 |
| Sidewall, % of width | 40 | 45 | +5 |
| Rim, in | 20 | 21 | +1 |
| Section height, in | 4.49 | 3.99 | -0.50 |
| Diameter, in | 28.98 | 28.97 | 0 (-0.0%) |
| Circumference, in | 91.0 | 91.0 | -0.0 |
| Revs per mile | 696 | 696 | +0 (+0.0%) |
Fitting 225/45R21 instead of 285/40R20
Within the usual 3% diameter guideline.
- Needs 21 in wheels.
- Shorter sidewall: 0.5 in less.
Cars with 285/40R20
Cars with 225/45R21
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