285/45R21 tire size in inches
A 285/45R21 tire measures
31.1" tall × 11.2" wide
5.05" sidewall on a 21" wheel. 649 revolutions per mile.
285/45R21 means a tire 285 mm wide, with sidewalls 45% as tall as the tire is wide (128 mm), radial construction (R), for a 21 inch wheel.
285/45R21 specs
| Overall diameter (height) | 31.10 inches (790 mm) |
|---|---|
| Section width | 11.22 inches (285 mm) |
| Sidewall height | 5.05 inches (128 mm) |
| Wheel (rim) diameter | 21 inches |
| Circumference | 97.7 inches (2,482 mm) |
| Revolutions per mile | 649 |
| Revolutions per kilometer | 403 |
| Approximate rim width | 9.5" to 11.0" |
| In inches (flotation style) | 31.1x11.2R21 |
| Aspect ratio | 45% |
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 285/45R21 on a 21" wheel
These 21" sizes are within 3% of 285/45R21's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 255/50R21 | 31.04" | 10.04" | −0.2% | 59.9 mph | Compare |
| 235/55R21 | 31.18" | 9.25" | +0.3% | 60.2 mph | Compare |
| 325/40R21 | 31.24" | 12.80" | +0.4% | 60.3 mph | Compare |
| 315/40R21 | 30.92" | 12.40" | −0.6% | 59.7 mph | Compare |
| 355/35R21 | 30.78" | 13.98" | −1.0% | 59.4 mph | Compare |
| 265/50R21 | 31.43" | 10.43" | +1.1% | 60.6 mph | Compare |
| 225/55R21 | 30.74" | 8.86" | −1.1% | 59.3 mph | Compare |
| 275/45R21 | 30.74" | 10.83" | −1.1% | 59.3 mph | Compare |
| 295/45R21 | 31.45" | 11.61" | +1.1% | 60.7 mph | Compare |
| 245/50R21 | 30.65" | 9.65" | −1.5% | 59.1 mph | Compare |
| 335/40R21 | 31.55" | 13.19" | +1.5% | 60.9 mph | Compare |
| 305/40R21 | 30.61" | 12.01" | −1.6% | 59.1 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 295/65R16 | 16" | 31.10" | 0.0% | Compare |
| 235/60R20 | 20" | 31.10" | 0.0% | Compare |
| 275/65R17 | 17" | 31.07" | −0.1% | Compare |
| 255/85R14 | 14" | 31.07" | −0.1% | Compare |
| 255/80R15 | 15" | 31.06" | −0.1% | Compare |
| 225/85R16 | 16" | 31.06" | −0.1% | Compare |
| 255/75R16 | 16" | 31.06" | −0.1% | Compare |
| 255/70R17 | 17" | 31.06" | −0.1% | Compare |
| 255/65R18 | 18" | 31.05" | −0.2% | Compare |
| 255/60R19 | 19" | 31.05" | −0.2% | Compare |
| 255/55R20 | 20" | 31.04" | −0.2% | Compare |
| 275/70R16 | 16" | 31.16" | +0.2% | Compare |
One size up or down
- 275/45R21narrower: 30.7" × 10.8"
- 295/45R21wider: 31.5" × 11.6"
- 285/40R21lower profile: 30.0" × 11.2"
- 285/50R21taller sidewall: 32.2" × 11.2"
Compare 285/45R21 with another size
Questions
- How tall is a 285/45R21 tire?
- A 285/45R21 tire is 31.1 inches tall (790 mm), calculated from the size. It is 11.2 inches wide with 5.0 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 285/45R21 mean?
- 285/45R21 means a tire 285 mm wide, with sidewalls 45% as tall as the tire is wide (128 mm), radial construction (R), for a 21 inch wheel.
- How many revolutions per mile does a 285/45R21 tire make?
- About 649 revolutions per mile, based on a circumference of 97.7 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 285/45R21 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 255/50R21 instead of 285/45R21?
- 255/50R21 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.