275/50R20 vs 255/50R21 tire size
255/50R21 vs 275/50R20, diameter
+0.7% taller
- Speedometer
- 59.6 mph
- At a true 60 mph
- Diameter
- 31.04 in
- Was 30.83 in
- Revs per mile
- 650
- Was 654
- 3% guideline
- Within
Car built for 275/50R20, now on 255/50R21.
275/50R20 and 255/50R21
| Measure | 275/50R20 | 255/50R21 | Difference |
|---|---|---|---|
| Width, mm | 275 | 255 | -20 |
| Sidewall, % of width | 50 | 50 | 0 |
| Rim, in | 20 | 21 | +1 |
| Section height, in | 5.41 | 5.02 | -0.39 |
| Diameter, in | 30.83 | 31.04 | +0.21 (+0.7%) |
| Circumference, in | 96.8 | 97.5 | +0.7 |
| Revs per mile | 654 | 650 | -4 (-0.7%) |
Fitting 255/50R21 instead of 275/50R20
Within the usual 3% diameter guideline.
- Needs 21 in wheels.
Cars with 275/50R20
Cars with 255/50R21
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