225/40R21 tire size in inches
A 225/40R21 tire measures
28.1" tall × 8.9" wide
3.54" sidewall on a 21" wheel. 718 revolutions per mile.
225/40R21 means a tire 225 mm wide, with sidewalls 40% as tall as the tire is wide (90 mm), radial construction (R), for a 21 inch wheel.
225/40R21 specs
| Overall diameter (height) | 28.09 inches (713 mm) |
|---|---|
| Section width | 8.86 inches (225 mm) |
| Sidewall height | 3.54 inches (90 mm) |
| Wheel (rim) diameter | 21 inches |
| Circumference | 88.2 inches (2,241 mm) |
| Revolutions per mile | 718 |
| Revolutions per kilometer | 446 |
| Approximate rim width | 7.5" to 9.0" |
| In inches (flotation style) | 28.1x8.9R21 |
| Aspect ratio | 40% |
Calculated from the size. Real tires differ by brand, model and tread depth, typically by a few tenths of an inch.
Sizes that can replace 225/40R21 on a 21" wheel
These 21" sizes are within 3% of 225/40R21's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 255/35R21 | 28.03" | 10.04" | −0.2% | 59.9 mph | Compare |
| 355/25R21 | 27.99" | 13.98" | −0.4% | 59.8 mph | Compare |
| 305/30R21 | 28.20" | 12.01" | +0.4% | 60.3 mph | Compare |
| 295/30R21 | 27.97" | 11.61" | −0.4% | 59.7 mph | Compare |
| 265/35R21 | 28.30" | 10.43" | +0.8% | 60.5 mph | Compare |
| 345/25R21 | 27.79" | 13.58" | −1.1% | 59.4 mph | Compare |
| 235/40R21 | 28.40" | 9.25" | +1.1% | 60.7 mph | Compare |
| 245/35R21 | 27.75" | 9.65" | −1.2% | 59.3 mph | Compare |
| 315/30R21 | 28.44" | 12.40" | +1.3% | 60.8 mph | Compare |
| 285/30R21 | 27.73" | 11.22" | −1.3% | 59.2 mph | Compare |
| 275/35R21 | 28.58" | 10.83" | +1.8% | 61.1 mph | Compare |
| 335/25R21 | 27.59" | 13.19" | −1.8% | 58.9 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 285/45R18 | 18" | 28.10" | 0.0% | Compare |
| 235/60R17 | 17" | 28.10" | +0.1% | Compare |
| 205/75R16 | 16" | 28.11" | +0.1% | Compare |
| 225/85R13 | 13" | 28.06" | −0.1% | Compare |
| 255/70R14 | 14" | 28.06" | −0.1% | Compare |
| 195/85R15 | 15" | 28.05" | −0.1% | Compare |
| 255/65R15 | 15" | 28.05" | −0.1% | Compare |
| 255/60R16 | 16" | 28.05" | −0.1% | Compare |
| 295/35R20 | 20" | 28.13" | +0.2% | Compare |
| 255/55R17 | 17" | 28.04" | −0.2% | Compare |
| 255/50R18 | 18" | 28.04" | −0.2% | Compare |
| 255/45R19 | 19" | 28.04" | −0.2% | Compare |
One size up or down
- 235/40R21wider: 28.4" × 9.3"
- 225/35R21lower profile: 27.2" × 8.9"
- 225/45R21taller sidewall: 29.0" × 8.9"
Compare 225/40R21 with another size
Questions
- How tall is a 225/40R21 tire?
- A 225/40R21 tire is 28.1 inches tall (713 mm), calculated from the size. It is 8.9 inches wide with 3.5 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 225/40R21 mean?
- 225/40R21 means a tire 225 mm wide, with sidewalls 40% as tall as the tire is wide (90 mm), radial construction (R), for a 21 inch wheel.
- How many revolutions per mile does a 225/40R21 tire make?
- About 718 revolutions per mile, based on a circumference of 88.2 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 225/40R21 tire?
- Roughly 7.5" to 9.0". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 255/35R21 instead of 225/40R21?
- 255/35R21 is −0.06 inches (−0.2%) in overall diameter, so at an indicated 60 mph you would be doing 59.9 mph. Differences under 3% are usually fine, but check clearance, load index and your vehicle's placard.