285/30R21 tire size in inches
A 285/30R21 tire measures
27.7" tall × 11.2" wide
3.37" sidewall on a 21" wheel. 727 revolutions per mile.
285/30R21 means a tire 285 mm wide, with sidewalls 30% as tall as the tire is wide (86 mm), radial construction (R), for a 21 inch wheel.
285/30R21 specs
| Overall diameter (height) | 27.73 inches (704 mm) |
|---|---|
| Section width | 11.22 inches (285 mm) |
| Sidewall height | 3.37 inches (86 mm) |
| Wheel (rim) diameter | 21 inches |
| Circumference | 87.1 inches (2,213 mm) |
| Revolutions per mile | 727 |
| Revolutions per kilometer | 452 |
| Approximate rim width | 9.5" to 11.0" |
| In inches (flotation style) | 27.7x11.2R21 |
| 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 285/30R21 on a 21" wheel
These 21" sizes are within 3% of 285/30R21's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 245/35R21 | 27.75" | 9.65" | +0.1% | 60.0 mph | Compare |
| 345/25R21 | 27.79" | 13.58" | +0.2% | 60.1 mph | Compare |
| 335/25R21 | 27.59" | 13.19" | −0.5% | 59.7 mph | Compare |
| 275/30R21 | 27.50" | 10.83" | −0.9% | 59.5 mph | Compare |
| 295/30R21 | 27.97" | 11.61" | +0.9% | 60.5 mph | Compare |
| 355/25R21 | 27.99" | 13.98" | +0.9% | 60.6 mph | Compare |
| 235/35R21 | 27.48" | 9.25" | −0.9% | 59.4 mph | Compare |
| 255/35R21 | 28.03" | 10.04" | +1.1% | 60.6 mph | Compare |
| 325/25R21 | 27.40" | 12.80" | −1.2% | 59.3 mph | Compare |
| 225/40R21 | 28.09" | 8.86" | +1.3% | 60.8 mph | Compare |
| 265/30R21 | 27.26" | 10.43" | −1.7% | 59.0 mph | Compare |
| 305/30R21 | 28.20" | 12.01" | +1.7% | 61.0 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 205/85R14 | 14" | 27.72" | 0.0% | Compare |
| 225/55R18 | 18" | 27.74" | 0.0% | Compare |
| 275/45R18 | 18" | 27.74" | 0.0% | Compare |
| 195/70R17 | 17" | 27.75" | +0.1% | Compare |
| 245/40R20 | 20" | 27.72" | −0.1% | Compare |
| 175/85R16 | 16" | 27.71" | −0.1% | Compare |
| 215/75R15 | 15" | 27.70" | −0.1% | Compare |
| 205/60R18 | 18" | 27.69" | −0.2% | Compare |
| 245/45R19 | 19" | 27.68" | −0.2% | Compare |
| 315/35R19 | 19" | 27.68" | −0.2% | Compare |
| 245/30R22 | 22" | 27.79" | +0.2% | Compare |
| 325/30R20 | 20" | 27.68" | −0.2% | Compare |
One size up or down
- 275/30R21narrower: 27.5" × 10.8"
- 295/30R21wider: 28.0" × 11.6"
- 285/25R21lower profile: 26.6" × 11.2"
- 285/35R21taller sidewall: 28.9" × 11.2"
Compare 285/30R21 with another size
Questions
- How tall is a 285/30R21 tire?
- A 285/30R21 tire is 27.7 inches tall (704 mm), calculated from the size. It is 11.2 inches wide with 3.4 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 285/30R21 mean?
- 285/30R21 means a tire 285 mm wide, with sidewalls 30% as tall as the tire is wide (86 mm), radial construction (R), for a 21 inch wheel.
- How many revolutions per mile does a 285/30R21 tire make?
- About 727 revolutions per mile, based on a circumference of 87.1 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 285/30R21 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 245/35R21 instead of 285/30R21?
- 245/35R21 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.