275/35R20 vs 275/30R21 tire size
275/30R21 vs 275/35R20, diameter
-0.3% shorter
- Speedometer
- 60.2 mph
- At a true 60 mph
- Diameter
- 27.50 in
- Was 27.58 in
- Revs per mile
- 733
- Was 731
- 3% guideline
- Within
Car built for 275/35R20, now on 275/30R21.
275/35R20 and 275/30R21
| Measure | 275/35R20 | 275/30R21 | Difference |
|---|---|---|---|
| Width, mm | 275 | 275 | 0 |
| Sidewall, % of width | 35 | 30 | -5 |
| Rim, in | 20 | 21 | +1 |
| Section height, in | 3.79 | 3.25 | -0.54 |
| Diameter, in | 27.58 | 27.50 | -0.08 (-0.3%) |
| Circumference, in | 86.6 | 86.4 | -0.3 |
| Revs per mile | 731 | 733 | +2 (+0.3%) |
Fitting 275/30R21 instead of 275/35R20
Within the usual 3% diameter guideline.
- Needs 21 in wheels.
- Shorter sidewall: 0.5 in less.
Cars with 275/35R20
Cars with 275/30R21
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