315/55R18 tire size in inches
A 315/55R18 tire measures
31.6" tall × 12.4" wide
6.82" sidewall on a 18" wheel. 637 revolutions per mile.
315/55R18 means a tire 315 mm wide, with sidewalls 55% as tall as the tire is wide (173 mm), radial construction (R), for a 18 inch wheel.
315/55R18 specs
| Overall diameter (height) | 31.64 inches (804 mm) |
|---|---|
| Section width | 12.40 inches (315 mm) |
| Sidewall height | 6.82 inches (173 mm) |
| Wheel (rim) diameter | 18 inches |
| Circumference | 99.4 inches (2,525 mm) |
| Revolutions per mile | 637 |
| Revolutions per kilometer | 396 |
| Approximate rim width | 9.0" to 10.5" |
| In inches (flotation style) | 31.6x12.4R18 |
| 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 315/55R18 on a 18" wheel
These 18" sizes are within 3% of 315/55R18's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 265/65R18 | 31.56" | 10.43" | −0.2% | 59.9 mph | Compare |
| 245/70R18 | 31.50" | 9.65" | −0.4% | 59.7 mph | Compare |
| 285/60R18 | 31.46" | 11.22" | −0.6% | 59.7 mph | Compare |
| 235/75R18 | 31.88" | 9.25" | +0.7% | 60.4 mph | Compare |
| 295/60R18 | 31.94" | 11.61" | +0.9% | 60.6 mph | Compare |
| 225/75R18 | 31.29" | 8.86" | −1.1% | 59.3 mph | Compare |
| 255/70R18 | 32.06" | 10.04" | +1.3% | 60.8 mph | Compare |
| 275/65R18 | 32.07" | 10.83" | +1.4% | 60.8 mph | Compare |
| 325/55R18 | 32.07" | 12.80" | +1.4% | 60.8 mph | Compare |
| 305/55R18 | 31.21" | 12.01" | −1.4% | 59.2 mph | Compare |
| 335/50R18 | 31.19" | 13.19" | −1.4% | 59.1 mph | Compare |
| 255/65R18 | 31.05" | 10.04" | −1.9% | 58.9 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 245/50R22 | 22" | 31.65" | 0.0% | Compare |
| 265/75R16 | 16" | 31.65" | 0.0% | Compare |
| 295/50R20 | 20" | 31.61" | −0.1% | Compare |
| 245/55R21 | 21" | 31.61" | −0.1% | Compare |
| 325/30R24 | 24" | 31.68" | +0.1% | Compare |
| 265/70R17 | 17" | 31.61" | −0.1% | Compare |
| 305/40R22 | 22" | 31.61" | −0.1% | Compare |
| 265/80R15 | 15" | 31.69" | +0.2% | Compare |
| 285/65R17 | 17" | 31.59" | −0.2% | Compare |
| 275/35R24 | 24" | 31.58" | −0.2% | Compare |
| 355/45R19 | 19" | 31.58" | −0.2% | Compare |
| 285/70R16 | 16" | 31.71" | +0.2% | Compare |
One size up or down
- 305/55R18narrower: 31.2" × 12.0"
- 325/55R18wider: 32.1" × 12.8"
- 315/50R18lower profile: 30.4" × 12.4"
- 315/60R18taller sidewall: 32.9" × 12.4"
Compare 315/55R18 with another size
Questions
- How tall is a 315/55R18 tire?
- A 315/55R18 tire is 31.6 inches tall (804 mm), calculated from the size. It is 12.4 inches wide with 6.8 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 315/55R18 mean?
- 315/55R18 means a tire 315 mm wide, with sidewalls 55% as tall as the tire is wide (173 mm), radial construction (R), for a 18 inch wheel.
- How many revolutions per mile does a 315/55R18 tire make?
- About 637 revolutions per mile, based on a circumference of 99.4 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 315/55R18 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 265/65R18 instead of 315/55R18?
- 265/65R18 is −0.08 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.