245/50R20 vs 275/40R21 tire size
275/40R21 vs 245/50R20, diameter
Same diameter
- Speedometer
- 60.0 mph
- At a true 60 mph
- Diameter
- 29.66 in
- Was 29.65 in
- Revs per mile
- 680
- Was 680
- 3% guideline
- Within
Car built for 245/50R20, now on 275/40R21.
245/50R20 and 275/40R21
| Measure | 245/50R20 | 275/40R21 | Difference |
|---|---|---|---|
| Width, mm | 245 | 275 | +30 |
| Sidewall, % of width | 50 | 40 | -10 |
| Rim, in | 20 | 21 | +1 |
| Section height, in | 4.82 | 4.33 | -0.49 |
| Diameter, in | 29.65 | 29.66 | +0.02 (+0.1%) |
| Circumference, in | 93.1 | 93.2 | +0.0 |
| Revs per mile | 680 | 680 | -0 (-0.1%) |
Fitting 275/40R21 instead of 245/50R20
Within the usual 3% diameter guideline.
- Needs 21 in wheels.
- 30 mm wider. Check rubbing at full lock.
Cars with 245/50R20
Cars with 275/40R21
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