245/55R21 tire size in inches
A 245/55R21 tire measures
31.6" tall × 9.6" wide
5.31" sidewall on a 21" wheel. 638 revolutions per mile.
245/55R21 means a tire 245 mm wide, with sidewalls 55% as tall as the tire is wide (135 mm), radial construction (R), for a 21 inch wheel.
245/55R21 specs
| Overall diameter (height) | 31.61 inches (803 mm) |
|---|---|
| Section width | 9.65 inches (245 mm) |
| Sidewall height | 5.31 inches (135 mm) |
| Wheel (rim) diameter | 21 inches |
| Circumference | 99.3 inches (2,522 mm) |
| Revolutions per mile | 638 |
| Revolutions per kilometer | 396 |
| Approximate rim width | 7.0" to 8.5" |
| In inches (flotation style) | 31.6x9.6R21 |
| 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 245/55R21 on a 21" wheel
These 21" sizes are within 3% of 245/55R21's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 335/40R21 | 31.55" | 13.19" | −0.2% | 59.9 mph | Compare |
| 295/45R21 | 31.45" | 11.61" | −0.5% | 59.7 mph | Compare |
| 265/50R21 | 31.43" | 10.43" | −0.6% | 59.7 mph | Compare |
| 305/45R21 | 31.81" | 12.01" | +0.6% | 60.4 mph | Compare |
| 275/50R21 | 31.83" | 10.83" | +0.7% | 60.4 mph | Compare |
| 345/40R21 | 31.87" | 13.58" | +0.8% | 60.5 mph | Compare |
| 325/40R21 | 31.24" | 12.80" | −1.2% | 59.3 mph | Compare |
| 235/55R21 | 31.18" | 9.25" | −1.4% | 59.2 mph | Compare |
| 255/55R21 | 32.04" | 10.04" | +1.4% | 60.8 mph | Compare |
| 285/45R21 | 31.10" | 11.22" | −1.6% | 59.0 mph | Compare |
| 315/45R21 | 32.16" | 12.40" | +1.7% | 61.0 mph | Compare |
| 255/50R21 | 31.04" | 10.04" | −1.8% | 58.9 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 265/70R17 | 17" | 31.61" | 0.0% | Compare |
| 305/40R22 | 22" | 31.61" | 0.0% | Compare |
| 295/50R20 | 20" | 31.61" | 0.0% | Compare |
| 285/65R17 | 17" | 31.59" | −0.1% | Compare |
| 275/35R24 | 24" | 31.58" | −0.1% | Compare |
| 355/45R19 | 19" | 31.58" | −0.1% | Compare |
| 315/55R18 | 18" | 31.64" | +0.1% | Compare |
| 245/60R20 | 20" | 31.57" | −0.1% | Compare |
| 245/50R22 | 22" | 31.65" | +0.1% | Compare |
| 265/75R16 | 16" | 31.65" | +0.1% | Compare |
| 265/65R18 | 18" | 31.56" | −0.1% | Compare |
| 325/30R24 | 24" | 31.68" | +0.2% | Compare |
One size up or down
Compare 245/55R21 with another size
Questions
- How tall is a 245/55R21 tire?
- A 245/55R21 tire is 31.6 inches tall (803 mm), calculated from the size. It is 9.6 inches wide with 5.3 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 245/55R21 mean?
- 245/55R21 means a tire 245 mm wide, with sidewalls 55% as tall as the tire is wide (135 mm), radial construction (R), for a 21 inch wheel.
- How many revolutions per mile does a 245/55R21 tire make?
- About 638 revolutions per mile, based on a circumference of 99.3 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 245/55R21 tire?
- Roughly 7.0" to 8.5". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 335/40R21 instead of 245/55R21?
- 335/40R21 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.