315/50R18 tire size in inches
A 315/50R18 tire measures
30.4" tall × 12.4" wide
6.20" sidewall on a 18" wheel. 663 revolutions per mile.
315/50R18 means a tire 315 mm wide, with sidewalls 50% as tall as the tire is wide (158 mm), radial construction (R), for a 18 inch wheel.
315/50R18 specs
| Overall diameter (height) | 30.40 inches (772 mm) |
|---|---|
| Section width | 12.40 inches (315 mm) |
| Sidewall height | 6.20 inches (158 mm) |
| Wheel (rim) diameter | 18 inches |
| Circumference | 95.5 inches (2,426 mm) |
| Revolutions per mile | 663 |
| Revolutions per kilometer | 412 |
| Approximate rim width | 9.0" to 10.5" |
| In inches (flotation style) | 30.4x12.4R18 |
| Aspect ratio | 50% |
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 315/50R18 on a 18" wheel
These 18" sizes are within 3% of 315/50R18's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 225/70R18 | 30.40" | 8.86" | 0.0% | 60.0 mph | Compare |
| 285/55R18 | 30.34" | 11.22" | −0.2% | 59.9 mph | Compare |
| 265/60R18 | 30.52" | 10.43" | +0.4% | 60.2 mph | Compare |
| 245/65R18 | 30.54" | 9.65" | +0.5% | 60.3 mph | Compare |
| 205/75R18 | 30.11" | 8.07" | −1.0% | 59.4 mph | Compare |
| 215/75R18 | 30.70" | 8.46" | +1.0% | 60.6 mph | Compare |
| 255/60R18 | 30.05" | 10.04" | −1.2% | 59.3 mph | Compare |
| 235/65R18 | 30.03" | 9.25" | −1.2% | 59.3 mph | Compare |
| 295/55R18 | 30.78" | 11.61" | +1.2% | 60.7 mph | Compare |
| 325/50R18 | 30.80" | 12.80" | +1.3% | 60.8 mph | Compare |
| 305/50R18 | 30.01" | 12.01" | −1.3% | 59.2 mph | Compare |
| 275/55R18 | 29.91" | 10.83" | −1.6% | 59.0 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 245/85R14 | 14" | 30.40" | 0.0% | Compare |
| 305/35R22 | 22" | 30.41" | 0.0% | Compare |
| 325/25R24 | 24" | 30.40" | 0.0% | Compare |
| 215/85R16 | 16" | 30.39" | 0.0% | Compare |
| 265/45R21 | 21" | 30.39" | 0.0% | Compare |
| 355/30R22 | 22" | 30.39" | −0.1% | Compare |
| 245/80R15 | 15" | 30.43" | +0.1% | Compare |
| 265/50R20 | 20" | 30.43" | +0.1% | Compare |
| 295/45R20 | 20" | 30.45" | +0.2% | Compare |
| 265/40R22 | 22" | 30.35" | −0.2% | Compare |
| 285/60R17 | 17" | 30.46" | +0.2% | Compare |
| 245/75R16 | 16" | 30.47" | +0.2% | Compare |
One size up or down
- 305/50R18narrower: 30.0" × 12.0"
- 325/50R18wider: 30.8" × 12.8"
- 315/45R18lower profile: 29.2" × 12.4"
- 315/55R18taller sidewall: 31.6" × 12.4"
Compare 315/50R18 with another size
Questions
- How tall is a 315/50R18 tire?
- A 315/50R18 tire is 30.4 inches tall (772 mm), calculated from the size. It is 12.4 inches wide with 6.2 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 315/50R18 mean?
- 315/50R18 means a tire 315 mm wide, with sidewalls 50% as tall as the tire is wide (158 mm), radial construction (R), for a 18 inch wheel.
- How many revolutions per mile does a 315/50R18 tire make?
- About 663 revolutions per mile, based on a circumference of 95.5 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 315/50R18 tire?
- Roughly 9.0" to 10.5". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 225/70R18 instead of 315/50R18?
- 225/70R18 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.