225/45R21 vs 245/40R21 tire size
245/40R21 vs 225/45R21, diameter
-0.9% shorter
- Speedometer
- 60.5 mph
- At a true 60 mph
- Diameter
- 28.72 in
- Was 28.97 in
- Revs per mile
- 702
- Was 696
- 3% guideline
- Within
Car built for 225/45R21, now on 245/40R21.
225/45R21 and 245/40R21
| Measure | 225/45R21 | 245/40R21 | Difference |
|---|---|---|---|
| Width, mm | 225 | 245 | +20 |
| Sidewall, % of width | 45 | 40 | -5 |
| Rim, in | 21 | 21 | 0 |
| Section height, in | 3.99 | 3.86 | -0.13 |
| Diameter, in | 28.97 | 28.72 | -0.26 (-0.9%) |
| Circumference, in | 91.0 | 90.2 | -0.8 |
| Revs per mile | 696 | 702 | +6 (+0.9%) |
Fitting 245/40R21 instead of 225/45R21
Within the usual 3% diameter guideline.
- 20 mm wider. Check rubbing at full lock.
Cars with 225/45R21
Cars with 245/40R21
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