305/45R20 tire size in inches
A 305/45R20 tire measures
30.8" tall × 12.0" wide
5.40" sidewall on a 20" wheel. 655 revolutions per mile.
305/45R20 means a tire 305 mm wide, with sidewalls 45% as tall as the tire is wide (137 mm), radial construction (R), for a 20 inch wheel.
305/45R20 specs
| Overall diameter (height) | 30.81 inches (783 mm) |
|---|---|
| Section width | 12.01 inches (305 mm) |
| Sidewall height | 5.40 inches (137 mm) |
| Wheel (rim) diameter | 20 inches |
| Circumference | 96.8 inches (2,458 mm) |
| Revolutions per mile | 655 |
| Revolutions per kilometer | 407 |
| Approximate rim width | 10.0" to 11.5" |
| In inches (flotation style) | 30.8x12.0R20 |
| 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 305/45R20 on a 20" wheel
These 20" sizes are within 3% of 305/45R20's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 275/50R20 | 30.83" | 10.83" | +0.1% | 60.0 mph | Compare |
| 345/40R20 | 30.87" | 13.58" | +0.2% | 60.1 mph | Compare |
| 225/60R20 | 30.63" | 8.86" | −0.6% | 59.7 mph | Compare |
| 215/65R20 | 31.00" | 8.46" | +0.6% | 60.4 mph | Compare |
| 245/55R20 | 30.61" | 9.65" | −0.6% | 59.6 mph | Compare |
| 255/55R20 | 31.04" | 10.04" | +0.8% | 60.5 mph | Compare |
| 335/40R20 | 30.55" | 13.19" | −0.8% | 59.5 mph | Compare |
| 235/60R20 | 31.10" | 9.25" | +1.0% | 60.6 mph | Compare |
| 315/45R20 | 31.16" | 12.40" | +1.2% | 60.7 mph | Compare |
| 295/45R20 | 30.45" | 11.61" | −1.2% | 59.3 mph | Compare |
| 265/50R20 | 30.43" | 10.43" | −1.2% | 59.3 mph | Compare |
| 355/40R20 | 31.18" | 13.98" | +1.2% | 60.7 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 235/80R16 | 16" | 30.80" | 0.0% | Compare |
| 325/50R18 | 18" | 30.80" | 0.0% | Compare |
| 345/25R24 | 24" | 30.79" | −0.1% | Compare |
| 355/35R21 | 21" | 30.78" | −0.1% | Compare |
| 295/55R18 | 18" | 30.78" | −0.1% | Compare |
| 225/55R21 | 21" | 30.74" | −0.2% | Compare |
| 275/45R21 | 21" | 30.74" | −0.2% | Compare |
| 335/45R19 | 19" | 30.87" | +0.2% | Compare |
| 235/75R17 | 17" | 30.88" | +0.2% | Compare |
| 285/30R24 | 24" | 30.73" | −0.2% | Compare |
| 235/85R15 | 15" | 30.73" | −0.3% | Compare |
| 285/70R15 | 15" | 30.71" | −0.3% | Compare |
One size up or down
- 295/45R20narrower: 30.5" × 11.6"
- 315/45R20wider: 31.2" × 12.4"
- 305/40R20lower profile: 29.6" × 12.0"
- 305/50R20taller sidewall: 32.0" × 12.0"
Compare 305/45R20 with another size
Questions
- How tall is a 305/45R20 tire?
- A 305/45R20 tire is 30.8 inches tall (783 mm), calculated from the size. It is 12.0 inches wide with 5.4 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 305/45R20 mean?
- 305/45R20 means a tire 305 mm wide, with sidewalls 45% as tall as the tire is wide (137 mm), radial construction (R), for a 20 inch wheel.
- How many revolutions per mile does a 305/45R20 tire make?
- About 655 revolutions per mile, based on a circumference of 96.8 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 305/45R20 tire?
- Roughly 10.0" to 11.5". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 275/50R20 instead of 305/45R20?
- 275/50R20 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.