315/45R18 tire size in inches
A 315/45R18 tire measures
29.2" tall × 12.4" wide
5.58" sidewall on a 18" wheel. 692 revolutions per mile.
315/45R18 means a tire 315 mm wide, with sidewalls 45% as tall as the tire is wide (142 mm), radial construction (R), for a 18 inch wheel.
315/45R18 specs
| Overall diameter (height) | 29.16 inches (741 mm) |
|---|---|
| Section width | 12.40 inches (315 mm) |
| Sidewall height | 5.58 inches (142 mm) |
| Wheel (rim) diameter | 18 inches |
| Circumference | 91.6 inches (2,327 mm) |
| Revolutions per mile | 692 |
| Revolutions per kilometer | 430 |
| Approximate rim width | 10.5" to 12.0" |
| In inches (flotation style) | 29.2x12.4R18 |
| 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 315/45R18 on a 18" wheel
These 18" sizes are within 3% of 315/45R18's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 235/60R18 | 29.10" | 9.25" | −0.2% | 59.9 mph | Compare |
| 285/50R18 | 29.22" | 11.22" | +0.2% | 60.1 mph | Compare |
| 255/55R18 | 29.04" | 10.04" | −0.4% | 59.8 mph | Compare |
| 205/70R18 | 29.30" | 8.07" | +0.5% | 60.3 mph | Compare |
| 215/65R18 | 29.00" | 8.46" | −0.5% | 59.7 mph | Compare |
| 265/55R18 | 29.48" | 10.43" | +1.1% | 60.6 mph | Compare |
| 275/50R18 | 28.83" | 10.83" | −1.1% | 59.3 mph | Compare |
| 305/45R18 | 28.81" | 12.01" | −1.2% | 59.3 mph | Compare |
| 195/75R18 | 29.52" | 7.68" | +1.2% | 60.7 mph | Compare |
| 225/65R18 | 29.52" | 8.86" | +1.2% | 60.7 mph | Compare |
| 325/45R18 | 29.52" | 12.80" | +1.2% | 60.7 mph | Compare |
| 195/70R18 | 28.75" | 7.68" | −1.4% | 59.1 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 215/60R19 | 19" | 29.16" | 0.0% | Compare |
| 345/30R21 | 21" | 29.15" | 0.0% | Compare |
| 225/80R15 | 15" | 29.17" | 0.0% | Compare |
| 235/55R19 | 19" | 29.18" | +0.1% | Compare |
| 295/35R21 | 21" | 29.13" | −0.1% | Compare |
| 305/30R22 | 22" | 29.20" | +0.1% | Compare |
| 205/75R17 | 17" | 29.11" | −0.2% | Compare |
| 265/25R24 | 24" | 29.22" | +0.2% | Compare |
| 285/45R19 | 19" | 29.10" | −0.2% | Compare |
| 335/35R20 | 20" | 29.23" | +0.2% | Compare |
| 325/40R19 | 19" | 29.24" | +0.3% | Compare |
| 275/65R15 | 15" | 29.07" | −0.3% | Compare |
One size up or down
- 305/45R18narrower: 28.8" × 12.0"
- 325/45R18wider: 29.5" × 12.8"
- 315/40R18lower profile: 27.9" × 12.4"
- 315/50R18taller sidewall: 30.4" × 12.4"
Compare 315/45R18 with another size
Questions
- How tall is a 315/45R18 tire?
- A 315/45R18 tire is 29.2 inches tall (741 mm), calculated from the size. It is 12.4 inches wide with 5.6 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 315/45R18 mean?
- 315/45R18 means a tire 315 mm wide, with sidewalls 45% as tall as the tire is wide (142 mm), radial construction (R), for a 18 inch wheel.
- How many revolutions per mile does a 315/45R18 tire make?
- About 692 revolutions per mile, based on a circumference of 91.6 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 315/45R18 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 235/60R18 instead of 315/45R18?
- 235/60R18 is −0.06 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.