285/40R18 tire size in inches
A 285/40R18 tire measures
27.0" tall × 11.2" wide
4.49" sidewall on a 18" wheel. 748 revolutions per mile.
285/40R18 means a tire 285 mm wide, with sidewalls 40% as tall as the tire is wide (114 mm), radial construction (R), for a 18 inch wheel.
285/40R18 specs
| Overall diameter (height) | 26.98 inches (685 mm) |
|---|---|
| Section width | 11.22 inches (285 mm) |
| Sidewall height | 4.49 inches (114 mm) |
| Wheel (rim) diameter | 18 inches |
| Circumference | 84.7 inches (2,153 mm) |
| Revolutions per mile | 748 |
| Revolutions per kilometer | 465 |
| Approximate rim width | 9.5" to 11.0" |
| In inches (flotation style) | 27.0x11.2R18 |
| 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 285/40R18 on a 18" wheel
These 18" sizes are within 3% of 285/40R18's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 325/35R18 | 26.96" | 12.80" | −0.1% | 60.0 mph | Compare |
| 255/45R18 | 27.04" | 10.04" | +0.2% | 60.1 mph | Compare |
| 205/55R18 | 26.88" | 8.07" | −0.4% | 59.8 mph | Compare |
| 225/50R18 | 26.86" | 8.86" | −0.4% | 59.7 mph | Compare |
| 195/60R18 | 27.21" | 7.68" | +0.9% | 60.5 mph | Compare |
| 335/35R18 | 27.23" | 13.19" | +0.9% | 60.6 mph | Compare |
| 235/50R18 | 27.25" | 9.25" | +1.0% | 60.6 mph | Compare |
| 245/45R18 | 26.68" | 9.65" | −1.1% | 59.3 mph | Compare |
| 315/35R18 | 26.68" | 12.40" | −1.1% | 59.3 mph | Compare |
| 275/40R18 | 26.66" | 10.83" | −1.2% | 59.3 mph | Compare |
| 295/40R18 | 27.29" | 11.61" | +1.2% | 60.7 mph | Compare |
| 215/55R18 | 27.31" | 8.46" | +1.2% | 60.7 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 225/45R19 | 19" | 26.97" | 0.0% | Compare |
| 195/65R17 | 17" | 26.98" | 0.0% | Compare |
| 295/30R20 | 20" | 26.97" | 0.0% | Compare |
| 355/25R20 | 20" | 26.99" | 0.0% | Compare |
| 235/70R14 | 14" | 26.95" | −0.1% | Compare |
| 215/65R16 | 16" | 27.00" | +0.1% | Compare |
| 305/25R21 | 21" | 27.00" | +0.1% | Compare |
| 255/25R22 | 22" | 27.02" | +0.2% | Compare |
| 175/80R16 | 16" | 27.02" | +0.2% | Compare |
| 255/30R21 | 21" | 27.02" | +0.2% | Compare |
| 185/75R16 | 16" | 26.93" | −0.2% | Compare |
| 235/65R15 | 15" | 27.03" | +0.2% | Compare |
One size up or down
- 275/40R18narrower: 26.7" × 10.8"
- 295/40R18wider: 27.3" × 11.6"
- 285/35R18lower profile: 25.9" × 11.2"
- 285/45R18taller sidewall: 28.1" × 11.2"
Compare 285/40R18 with another size
Questions
- How tall is a 285/40R18 tire?
- A 285/40R18 tire is 27.0 inches tall (685 mm), calculated from the size. It is 11.2 inches wide with 4.5 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 285/40R18 mean?
- 285/40R18 means a tire 285 mm wide, with sidewalls 40% as tall as the tire is wide (114 mm), radial construction (R), for a 18 inch wheel.
- How many revolutions per mile does a 285/40R18 tire make?
- About 748 revolutions per mile, based on a circumference of 84.7 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 285/40R18 tire?
- Roughly 9.5" to 11.0". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 325/35R18 instead of 285/40R18?
- 325/35R18 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.