355/40R21 tire size in inches
A 355/40R21 tire measures
32.2" tall × 14.0" wide
5.59" sidewall on a 21" wheel. 627 revolutions per mile.
355/40R21 means a tire 355 mm wide, with sidewalls 40% as tall as the tire is wide (142 mm), radial construction (R), for a 21 inch wheel.
355/40R21 specs
| Overall diameter (height) | 32.18 inches (817 mm) |
|---|---|
| Section width | 13.98 inches (355 mm) |
| Sidewall height | 5.59 inches (142 mm) |
| Wheel (rim) diameter | 21 inches |
| Circumference | 101.1 inches (2,568 mm) |
| Revolutions per mile | 627 |
| Revolutions per kilometer | 389 |
| Approximate rim width | 11.5" to 13.0" |
| In inches (flotation style) | 32.2x14.0R21 |
| 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 355/40R21 on a 21" wheel
These 21" sizes are within 3% of 355/40R21's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 315/45R21 | 32.16" | 12.40" | −0.1% | 60.0 mph | Compare |
| 285/50R21 | 32.22" | 11.22" | +0.1% | 60.1 mph | Compare |
| 255/55R21 | 32.04" | 10.04" | −0.4% | 59.7 mph | Compare |
| 265/55R21 | 32.48" | 10.43" | +0.9% | 60.6 mph | Compare |
| 345/40R21 | 31.87" | 13.58" | −1.0% | 59.4 mph | Compare |
| 325/45R21 | 32.52" | 12.80" | +1.0% | 60.6 mph | Compare |
| 275/50R21 | 31.83" | 10.83" | −1.1% | 59.3 mph | Compare |
| 305/45R21 | 31.81" | 12.01" | −1.2% | 59.3 mph | Compare |
| 295/50R21 | 32.61" | 11.61" | +1.3% | 60.8 mph | Compare |
| 245/55R21 | 31.61" | 9.65" | −1.8% | 58.9 mph | Compare |
| 335/40R21 | 31.55" | 13.19" | −2.0% | 58.8 mph | Compare |
| 335/45R21 | 32.87" | 13.19" | +2.1% | 61.3 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 235/55R22 | 22" | 32.18" | 0.0% | Compare |
| 335/50R19 | 19" | 32.19" | 0.0% | Compare |
| 275/70R17 | 17" | 32.16" | −0.1% | Compare |
| 305/55R19 | 19" | 32.21" | +0.1% | Compare |
| 345/30R24 | 24" | 32.15" | −0.1% | Compare |
| 345/45R20 | 20" | 32.22" | +0.1% | Compare |
| 295/35R24 | 24" | 32.13" | −0.2% | Compare |
| 325/40R22 | 22" | 32.24" | +0.2% | Compare |
| 275/75R16 | 16" | 32.24" | +0.2% | Compare |
| 295/70R16 | 16" | 32.26" | +0.2% | Compare |
| 285/45R22 | 22" | 32.10" | −0.3% | Compare |
| 295/65R17 | 17" | 32.10" | −0.3% | Compare |
One size up or down
- 345/40R21narrower: 31.9" × 13.6"
- 355/35R21lower profile: 30.8" × 14.0"
- 355/45R21taller sidewall: 33.6" × 14.0"
Compare 355/40R21 with another size
Questions
- How tall is a 355/40R21 tire?
- A 355/40R21 tire is 32.2 inches tall (817 mm), calculated from the size. It is 14.0 inches wide with 5.6 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 355/40R21 mean?
- 355/40R21 means a tire 355 mm wide, with sidewalls 40% as tall as the tire is wide (142 mm), radial construction (R), for a 21 inch wheel.
- How many revolutions per mile does a 355/40R21 tire make?
- About 627 revolutions per mile, based on a circumference of 101.1 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 355/40R21 tire?
- Roughly 11.5" to 13.0". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 315/45R21 instead of 355/40R21?
- 315/45R21 is −0.02 inches (−0.1%) in overall diameter, so at an indicated 60 mph you would be doing 60.0 mph. Differences under 3% are usually fine, but check clearance, load index and your vehicle's placard.