325/30R21 tire size in inches
A 325/30R21 tire measures
28.7" tall × 12.8" wide
3.84" sidewall on a 21" wheel. 703 revolutions per mile.
325/30R21 means a tire 325 mm wide, with sidewalls 30% as tall as the tire is wide (98 mm), radial construction (R), for a 21 inch wheel.
325/30R21 specs
| Overall diameter (height) | 28.68 inches (728 mm) |
|---|---|
| Section width | 12.80 inches (325 mm) |
| Sidewall height | 3.84 inches (98 mm) |
| Wheel (rim) diameter | 21 inches |
| Circumference | 90.1 inches (2,288 mm) |
| Revolutions per mile | 703 |
| Revolutions per kilometer | 437 |
| Approximate rim width | 10.5" to 12.0" |
| In inches (flotation style) | 28.7x12.8R21 |
| Aspect ratio | 30% |
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 325/30R21 on a 21" wheel
These 21" sizes are within 3% of 325/30R21's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 245/40R21 | 28.72" | 9.65" | +0.1% | 60.1 mph | Compare |
| 275/35R21 | 28.58" | 10.83" | −0.3% | 59.8 mph | Compare |
| 285/35R21 | 28.85" | 11.22" | +0.6% | 60.4 mph | Compare |
| 335/30R21 | 28.91" | 13.19" | +0.8% | 60.5 mph | Compare |
| 315/30R21 | 28.44" | 12.40" | −0.8% | 59.5 mph | Compare |
| 235/40R21 | 28.40" | 9.25" | −1.0% | 59.4 mph | Compare |
| 225/45R21 | 28.97" | 8.86" | +1.0% | 60.6 mph | Compare |
| 255/40R21 | 29.03" | 10.04" | +1.2% | 60.7 mph | Compare |
| 265/35R21 | 28.30" | 10.43" | −1.3% | 59.2 mph | Compare |
| 295/35R21 | 29.13" | 11.61" | +1.6% | 60.9 mph | Compare |
| 345/30R21 | 29.15" | 13.58" | +1.6% | 61.0 mph | Compare |
| 305/30R21 | 28.20" | 12.01" | −1.6% | 59.0 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 245/45R20 | 20" | 28.68" | 0.0% | Compare |
| 315/35R20 | 20" | 28.68" | 0.0% | Compare |
| 205/60R19 | 19" | 28.69" | 0.0% | Compare |
| 275/40R20 | 20" | 28.66" | −0.1% | Compare |
| 215/75R16 | 16" | 28.70" | +0.1% | Compare |
| 245/50R19 | 19" | 28.65" | −0.1% | Compare |
| 205/85R15 | 15" | 28.72" | +0.2% | Compare |
| 225/60R18 | 18" | 28.63" | −0.2% | Compare |
| 235/85R13 | 13" | 28.73" | +0.2% | Compare |
| 285/30R22 | 22" | 28.73" | +0.2% | Compare |
| 295/50R17 | 17" | 28.61" | −0.2% | Compare |
| 225/55R19 | 19" | 28.74" | +0.2% | Compare |
One size up or down
- 315/30R21narrower: 28.4" × 12.4"
- 335/30R21wider: 28.9" × 13.2"
- 325/25R21lower profile: 27.4" × 12.8"
- 325/35R21taller sidewall: 30.0" × 12.8"
Compare 325/30R21 with another size
Questions
- How tall is a 325/30R21 tire?
- A 325/30R21 tire is 28.7 inches tall (728 mm), calculated from the size. It is 12.8 inches wide with 3.8 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 325/30R21 mean?
- 325/30R21 means a tire 325 mm wide, with sidewalls 30% as tall as the tire is wide (98 mm), radial construction (R), for a 21 inch wheel.
- How many revolutions per mile does a 325/30R21 tire make?
- About 703 revolutions per mile, based on a circumference of 90.1 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 325/30R21 tire?
- Roughly 10.5" to 12.0". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 245/40R21 instead of 325/30R21?
- 245/40R21 is +0.04 inches (+0.1%) in overall diameter, so at an indicated 60 mph you would be doing 60.1 mph. Differences under 3% are usually fine, but check clearance, load index and your vehicle's placard.