315/40R20 tire size in inches
A 315/40R20 tire measures
29.9" tall × 12.4" wide
4.96" sidewall on a 20" wheel. 674 revolutions per mile.
315/40R20 means a tire 315 mm wide, with sidewalls 40% as tall as the tire is wide (126 mm), radial construction (R), for a 20 inch wheel.
315/40R20 specs
| Overall diameter (height) | 29.92 inches (760 mm) |
|---|---|
| Section width | 12.40 inches (315 mm) |
| Sidewall height | 4.96 inches (126 mm) |
| Wheel (rim) diameter | 20 inches |
| Circumference | 94.0 inches (2,388 mm) |
| Revolutions per mile | 674 |
| Revolutions per kilometer | 419 |
| Approximate rim width | 10.5" to 12.0" |
| In inches (flotation style) | 29.9x12.4R20 |
| Aspect ratio | 40% |
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 315/40R20 on a 20" wheel
These 20" sizes are within 3% of 315/40R20's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 255/50R20 | 30.04" | 10.04" | +0.4% | 60.2 mph | Compare |
| 355/35R20 | 29.78" | 13.98" | −0.5% | 59.7 mph | Compare |
| 225/55R20 | 29.74" | 8.86" | −0.6% | 59.6 mph | Compare |
| 275/45R20 | 29.74" | 10.83" | −0.6% | 59.6 mph | Compare |
| 285/45R20 | 30.10" | 11.22" | +0.6% | 60.4 mph | Compare |
| 215/60R20 | 30.16" | 8.46" | +0.8% | 60.5 mph | Compare |
| 235/55R20 | 30.18" | 9.25" | +0.9% | 60.5 mph | Compare |
| 245/50R20 | 29.65" | 9.65" | −0.9% | 59.4 mph | Compare |
| 305/40R20 | 29.61" | 12.01" | −1.1% | 59.4 mph | Compare |
| 325/40R20 | 30.24" | 12.80" | +1.1% | 60.6 mph | Compare |
| 345/35R20 | 29.51" | 13.58" | −1.4% | 59.2 mph | Compare |
| 265/50R20 | 30.43" | 10.43" | +1.7% | 61.0 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 335/30R22 | 22" | 29.91" | 0.0% | Compare |
| 275/55R18 | 18" | 29.91" | 0.0% | Compare |
| 295/60R16 | 16" | 29.94" | +0.1% | Compare |
| 235/70R17 | 17" | 29.95" | +0.1% | Compare |
| 325/35R21 | 21" | 29.96" | +0.1% | Compare |
| 235/75R16 | 16" | 29.88" | −0.1% | Compare |
| 335/45R18 | 18" | 29.87" | −0.2% | Compare |
| 285/40R21 | 21" | 29.98" | +0.2% | Compare |
| 345/40R19 | 19" | 29.87" | −0.2% | Compare |
| 225/50R21 | 21" | 29.86" | −0.2% | Compare |
| 285/35R22 | 22" | 29.85" | −0.2% | Compare |
| 215/70R18 | 18" | 29.85" | −0.2% | Compare |
One size up or down
- 305/40R20narrower: 29.6" × 12.0"
- 325/40R20wider: 30.2" × 12.8"
- 315/35R20lower profile: 28.7" × 12.4"
- 315/45R20taller sidewall: 31.2" × 12.4"
Compare 315/40R20 with another size
Questions
- How tall is a 315/40R20 tire?
- A 315/40R20 tire is 29.9 inches tall (760 mm), calculated from the size. It is 12.4 inches wide with 5.0 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 315/40R20 mean?
- 315/40R20 means a tire 315 mm wide, with sidewalls 40% as tall as the tire is wide (126 mm), radial construction (R), for a 20 inch wheel.
- How many revolutions per mile does a 315/40R20 tire make?
- About 674 revolutions per mile, based on a circumference of 94.0 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 315/40R20 tire?
- Roughly 10.5" to 12.0". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 255/50R20 instead of 315/40R20?
- 255/50R20 is +0.12 inches (+0.4%) in overall diameter, so at an indicated 60 mph you would be doing 60.2 mph. Differences under 3% are usually fine, but check clearance, load index and your vehicle's placard.