255/60R20 vs 275/55R21 tire size
275/55R21 vs 255/60R20, diameter
+2.7% taller
- Speedometer
- 58.4 mph
- At a true 60 mph
- Diameter
- 32.91 in
- Was 32.05 in
- Revs per mile
- 613
- Was 629
- 3% guideline
- Within
Car built for 255/60R20, now on 275/55R21.
255/60R20 and 275/55R21
| Measure | 255/60R20 | 275/55R21 | Difference |
|---|---|---|---|
| Width, mm | 255 | 275 | +20 |
| Sidewall, % of width | 60 | 55 | -5 |
| Rim, in | 20 | 21 | +1 |
| Section height, in | 6.02 | 5.95 | -0.07 |
| Diameter, in | 32.05 | 32.91 | +0.86 (+2.7%) |
| Circumference, in | 100.7 | 103.4 | +2.7 |
| Revs per mile | 629 | 613 | -16 (-2.6%) |
Fitting 275/55R21 instead of 255/60R20
Within the usual 3% diameter guideline.
- Needs 21 in wheels.
- 20 mm wider. Check rubbing at full lock.
Cars with 255/60R20
Cars with 275/55R21
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