245/45R21 tire size in inches
A 245/45R21 tire measures
29.7" tall × 9.6" wide
4.34" sidewall on a 21" wheel. 679 revolutions per mile.
245/45R21 means a tire 245 mm wide, with sidewalls 45% as tall as the tire is wide (110 mm), radial construction (R), for a 21 inch wheel.
245/45R21 specs
| Overall diameter (height) | 29.68 inches (754 mm) |
|---|---|
| Section width | 9.65 inches (245 mm) |
| Sidewall height | 4.34 inches (110 mm) |
| Wheel (rim) diameter | 21 inches |
| Circumference | 93.2 inches (2,368 mm) |
| Revolutions per mile | 679 |
| Revolutions per kilometer | 422 |
| Approximate rim width | 8.0" to 9.5" |
| In inches (flotation style) | 29.7x9.6R21 |
| 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 245/45R21 on a 21" wheel
These 21" sizes are within 3% of 245/45R21's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 315/35R21 | 29.68" | 12.40" | 0.0% | 60.0 mph | Compare |
| 275/40R21 | 29.66" | 10.83" | −0.1% | 60.0 mph | Compare |
| 225/50R21 | 29.86" | 8.86" | +0.6% | 60.4 mph | Compare |
| 305/35R21 | 29.41" | 12.01" | −0.9% | 59.4 mph | Compare |
| 325/35R21 | 29.96" | 12.80" | +0.9% | 60.6 mph | Compare |
| 285/40R21 | 29.98" | 11.22" | +1.0% | 60.6 mph | Compare |
| 355/30R21 | 29.39" | 13.98" | −1.0% | 59.4 mph | Compare |
| 265/40R21 | 29.35" | 10.43" | −1.1% | 59.3 mph | Compare |
| 255/45R21 | 30.04" | 10.04" | +1.2% | 60.7 mph | Compare |
| 235/45R21 | 29.33" | 9.25" | −1.2% | 59.3 mph | Compare |
| 345/30R21 | 29.15" | 13.58" | −1.8% | 58.9 mph | Compare |
| 335/35R21 | 30.23" | 13.19" | +1.9% | 61.1 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 325/30R22 | 22" | 29.68" | 0.0% | Compare |
| 215/75R17 | 17" | 29.70" | +0.1% | Compare |
| 265/75R14 | 14" | 29.65" | −0.1% | Compare |
| 245/50R20 | 20" | 29.65" | −0.1% | Compare |
| 245/40R22 | 22" | 29.72" | +0.1% | Compare |
| 205/85R16 | 16" | 29.72" | +0.1% | Compare |
| 235/85R14 | 14" | 29.73" | +0.2% | Compare |
| 225/60R19 | 19" | 29.63" | −0.2% | Compare |
| 225/55R20 | 20" | 29.74" | +0.2% | Compare |
| 275/45R20 | 20" | 29.74" | +0.2% | Compare |
| 295/50R18 | 18" | 29.61" | −0.2% | Compare |
| 245/55R19 | 19" | 29.61" | −0.2% | Compare |
One size up or down
- 235/45R21narrower: 29.3" × 9.3"
- 255/45R21wider: 30.0" × 10.0"
- 245/40R21lower profile: 28.7" × 9.6"
- 245/50R21taller sidewall: 30.6" × 9.6"
Compare 245/45R21 with another size
Questions
- How tall is a 245/45R21 tire?
- A 245/45R21 tire is 29.7 inches tall (754 mm), calculated from the size. It is 9.6 inches wide with 4.3 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 245/45R21 mean?
- 245/45R21 means a tire 245 mm wide, with sidewalls 45% as tall as the tire is wide (110 mm), radial construction (R), for a 21 inch wheel.
- How many revolutions per mile does a 245/45R21 tire make?
- About 679 revolutions per mile, based on a circumference of 93.2 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 245/45R21 tire?
- Roughly 8.0" to 9.5". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 315/35R21 instead of 245/45R21?
- 315/35R21 is 0.00 inches (0.0%) 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.