245/45R21 vs 265/40R21 tire size
265/40R21 vs 245/45R21, diameter
-1.1% shorter
- Speedometer
- 60.7 mph
- At a true 60 mph
- Diameter
- 29.35 in
- Was 29.68 in
- Revs per mile
- 687
- Was 679
- 3% guideline
- Within
Car built for 245/45R21, now on 265/40R21.
245/45R21 and 265/40R21
| Measure | 245/45R21 | 265/40R21 | Difference |
|---|---|---|---|
| Width, mm | 245 | 265 | +20 |
| Sidewall, % of width | 45 | 40 | -5 |
| Rim, in | 21 | 21 | 0 |
| Section height, in | 4.34 | 4.17 | -0.17 |
| Diameter, in | 29.68 | 29.35 | -0.33 (-1.1%) |
| Circumference, in | 93.2 | 92.2 | -1.1 |
| Revs per mile | 679 | 687 | +8 (+1.1%) |
Fitting 265/40R21 instead of 245/45R21
Within the usual 3% diameter guideline.
- 20 mm wider. Check rubbing at full lock.
Cars with 245/45R21
Cars with 265/40R21
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