265/40R20 vs 255/35R21 tire size
255/35R21 vs 265/40R20, diameter
-1.1% shorter
- Speedometer
- 60.7 mph
- At a true 60 mph
- Diameter
- 28.03 in
- Was 28.35 in
- Revs per mile
- 720
- Was 711
- 3% guideline
- Within
Car built for 265/40R20, now on 255/35R21.
265/40R20 and 255/35R21
| Measure | 265/40R20 | 255/35R21 | Difference |
|---|---|---|---|
| Width, mm | 265 | 255 | -10 |
| Sidewall, % of width | 40 | 35 | -5 |
| Rim, in | 20 | 21 | +1 |
| Section height, in | 4.17 | 3.51 | -0.66 |
| Diameter, in | 28.35 | 28.03 | -0.32 (-1.1%) |
| Circumference, in | 89.1 | 88.1 | -1.0 |
| Revs per mile | 711 | 720 | +8 (+1.1%) |
Fitting 255/35R21 instead of 265/40R20
Within the usual 3% diameter guideline.
- Needs 21 in wheels.
- Shorter sidewall: 0.7 in less.
Cars with 265/40R20
Cars with 255/35R21
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