325/55R21 tire size in inches
A 325/55R21 tire measures
35.1" tall × 12.8" wide
7.04" sidewall on a 21" wheel. 575 revolutions per mile.
325/55R21 means a tire 325 mm wide, with sidewalls 55% as tall as the tire is wide (179 mm), radial construction (R), for a 21 inch wheel.
325/55R21 specs
| Overall diameter (height) | 35.07 inches (891 mm) |
|---|---|
| Section width | 12.80 inches (325 mm) |
| Sidewall height | 7.04 inches (179 mm) |
| Wheel (rim) diameter | 21 inches |
| Circumference | 110.2 inches (2,799 mm) |
| Revolutions per mile | 575 |
| Revolutions per kilometer | 357 |
| Approximate rim width | 9.5" to 11.0" |
| In inches (flotation style) | 35.1x12.8R21 |
| Aspect ratio | 55% |
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 325/55R21 on a 21" wheel
These 21" sizes are within 3% of 325/55R21's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 355/50R21 | 34.98" | 13.98" | −0.3% | 59.8 mph | Compare |
| 315/55R21 | 34.64" | 12.40" | −1.2% | 59.3 mph | Compare |
| 335/55R21 | 35.51" | 13.19" | +1.2% | 60.7 mph | Compare |
| 345/50R21 | 34.58" | 13.58" | −1.4% | 59.2 mph | Compare |
| 305/55R21 | 34.21" | 12.01" | −2.5% | 58.5 mph | Compare |
| 345/55R21 | 35.94" | 13.58" | +2.5% | 61.5 mph | Compare |
| 335/50R21 | 34.19" | 13.19" | −2.5% | 58.5 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 285/85R16 | 16" | 35.07" | 0.0% | Compare |
| 295/65R20 | 20" | 35.10" | +0.1% | Compare |
| 315/65R19 | 19" | 35.12" | +0.1% | Compare |
| 305/75R17 | 17" | 35.01" | −0.2% | Compare |
| 335/65R18 | 18" | 35.15" | +0.2% | Compare |
| 35x12.50R15 | 15" | 35.00" | −0.2% | Compare |
| 35x12.50R17 | 17" | 35.00" | −0.2% | Compare |
| 35x12.50R18 | 18" | 35.00" | −0.2% | Compare |
| 35x12.50R20 | 20" | 35.00" | −0.2% | Compare |
| 35x12.50R22 | 22" | 35.00" | −0.2% | Compare |
| 35x12.50R24 | 24" | 35.00" | −0.2% | Compare |
| 355/40R24 | 24" | 35.18" | +0.3% | Compare |
One size up or down
Compare 325/55R21 with another size
Questions
- How tall is a 325/55R21 tire?
- A 325/55R21 tire is 35.1 inches tall (891 mm), calculated from the size. It is 12.8 inches wide with 7.0 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 325/55R21 mean?
- 325/55R21 means a tire 325 mm wide, with sidewalls 55% as tall as the tire is wide (179 mm), radial construction (R), for a 21 inch wheel.
- How many revolutions per mile does a 325/55R21 tire make?
- About 575 revolutions per mile, based on a circumference of 110.2 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 325/55R21 tire?
- Roughly 9.5" to 11.0". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 355/50R21 instead of 325/55R21?
- 355/50R21 is −0.10 inches (−0.3%) in overall diameter, so at an indicated 60 mph you would be doing 59.8 mph. Differences under 3% are usually fine, but check clearance, load index and your vehicle's placard.