215/40R18 tire size in inches
A 215/40R18 tire measures
24.8" tall × 8.5" wide
3.39" sidewall on a 18" wheel. 814 revolutions per mile.
215/40R18 means a tire 215 mm wide, with sidewalls 40% as tall as the tire is wide (86 mm), radial construction (R), for a 18 inch wheel.
215/40R18 specs
| Overall diameter (height) | 24.77 inches (629 mm) |
|---|---|
| Section width | 8.46 inches (215 mm) |
| Sidewall height | 3.39 inches (86 mm) |
| Wheel (rim) diameter | 18 inches |
| Circumference | 77.8 inches (1,977 mm) |
| Revolutions per mile | 814 |
| Revolutions per kilometer | 506 |
| Approximate rim width | 7.0" to 8.5" |
| In inches (flotation style) | 24.8x8.5R18 |
| 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 215/40R18 on a 18" wheel
These 18" sizes are within 3% of 215/40R18's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 245/35R18 | 24.75" | 9.65" | −0.1% | 60.0 mph | Compare |
| 195/45R18 | 24.91" | 7.68" | +0.6% | 60.3 mph | Compare |
| 255/35R18 | 25.03" | 10.04" | +1.0% | 60.6 mph | Compare |
| 235/35R18 | 24.48" | 9.25" | −1.2% | 59.3 mph | Compare |
| 225/40R18 | 25.09" | 8.86" | +1.3% | 60.8 mph | Compare |
| 205/40R18 | 24.46" | 8.07" | −1.3% | 59.2 mph | Compare |
| 205/45R18 | 25.26" | 8.07" | +2.0% | 61.2 mph | Compare |
| 265/35R18 | 25.30" | 10.43" | +2.1% | 61.3 mph | Compare |
| 225/35R18 | 24.20" | 8.86" | −2.3% | 58.6 mph | Compare |
| 235/40R18 | 25.40" | 9.25" | +2.5% | 61.5 mph | Compare |
| 195/40R18 | 24.14" | 7.68" | −2.5% | 58.5 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 245/30R19 | 19" | 24.79" | +0.1% | Compare |
| 195/70R14 | 14" | 24.75" | −0.1% | Compare |
| 165/75R15 | 15" | 24.74" | −0.1% | Compare |
| 225/55R15 | 15" | 24.74" | −0.1% | Compare |
| 275/45R15 | 15" | 24.74" | −0.1% | Compare |
| 185/60R16 | 16" | 24.74" | −0.1% | Compare |
| 295/25R19 | 19" | 24.81" | +0.1% | Compare |
| 245/25R20 | 20" | 24.82" | +0.2% | Compare |
| 245/40R17 | 17" | 24.72" | −0.2% | Compare |
| 175/85R13 | 13" | 24.71" | −0.2% | Compare |
| 215/70R13 | 13" | 24.85" | +0.3% | Compare |
| 285/35R17 | 17" | 24.85" | +0.3% | Compare |
One size up or down
- 205/40R18narrower: 24.5" × 8.1"
- 225/40R18wider: 25.1" × 8.9"
- 215/35R18lower profile: 23.9" × 8.5"
- 215/45R18taller sidewall: 25.6" × 8.5"
Compare 215/40R18 with another size
Questions
- How tall is a 215/40R18 tire?
- A 215/40R18 tire is 24.8 inches tall (629 mm), calculated from the size. It is 8.5 inches wide with 3.4 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 215/40R18 mean?
- 215/40R18 means a tire 215 mm wide, with sidewalls 40% as tall as the tire is wide (86 mm), radial construction (R), for a 18 inch wheel.
- How many revolutions per mile does a 215/40R18 tire make?
- About 814 revolutions per mile, based on a circumference of 77.8 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 215/40R18 tire?
- Roughly 7.0" to 8.5". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 245/35R18 instead of 215/40R18?
- 245/35R18 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.