245/40R18 tire size in inches
A 245/40R18 tire measures
25.7" tall × 9.6" wide
3.86" sidewall on a 18" wheel. 784 revolutions per mile.
245/40R18 means a tire 245 mm wide, with sidewalls 40% as tall as the tire is wide (98 mm), radial construction (R), for a 18 inch wheel.
245/40R18 specs
| Overall diameter (height) | 25.72 inches (653 mm) |
|---|---|
| Section width | 9.65 inches (245 mm) |
| Sidewall height | 3.86 inches (98 mm) |
| Wheel (rim) diameter | 18 inches |
| Circumference | 80.8 inches (2,052 mm) |
| Revolutions per mile | 784 |
| Revolutions per kilometer | 487 |
| Approximate rim width | 8.0" to 9.5" |
| In inches (flotation style) | 25.7x9.6R18 |
| 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 245/40R18 on a 18" wheel
These 18" sizes are within 3% of 245/40R18's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 195/50R18 | 25.68" | 7.68" | −0.2% | 59.9 mph | Compare |
| 215/45R18 | 25.62" | 8.46" | −0.4% | 59.8 mph | Compare |
| 275/35R18 | 25.58" | 10.83" | −0.5% | 59.7 mph | Compare |
| 285/35R18 | 25.85" | 11.22" | +0.5% | 60.3 mph | Compare |
| 225/45R18 | 25.97" | 8.86" | +1.0% | 60.6 mph | Compare |
| 235/40R18 | 25.40" | 9.25" | −1.2% | 59.3 mph | Compare |
| 255/40R18 | 26.03" | 10.04" | +1.2% | 60.7 mph | Compare |
| 205/50R18 | 26.07" | 8.07" | +1.4% | 60.8 mph | Compare |
| 265/35R18 | 25.30" | 10.43" | −1.6% | 59.0 mph | Compare |
| 295/35R18 | 26.13" | 11.61" | +1.6% | 61.0 mph | Compare |
| 205/45R18 | 25.26" | 8.07" | −1.8% | 58.9 mph | Compare |
| 235/45R18 | 26.33" | 9.25" | +2.4% | 61.4 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 175/85R14 | 14" | 25.71" | 0.0% | Compare |
| 285/30R19 | 19" | 25.73" | +0.1% | Compare |
| 215/75R13 | 13" | 25.70" | −0.1% | Compare |
| 185/60R17 | 17" | 25.74" | +0.1% | Compare |
| 225/55R16 | 16" | 25.74" | +0.1% | Compare |
| 275/45R16 | 16" | 25.74" | +0.1% | Compare |
| 195/70R15 | 15" | 25.75" | +0.1% | Compare |
| 205/60R16 | 16" | 25.69" | −0.1% | Compare |
| 245/45R17 | 17" | 25.68" | −0.1% | Compare |
| 245/35R19 | 19" | 25.75" | +0.1% | Compare |
| 315/35R17 | 17" | 25.68" | −0.1% | Compare |
| 215/40R19 | 19" | 25.77" | +0.2% | Compare |
One size up or down
- 235/40R18narrower: 25.4" × 9.3"
- 255/40R18wider: 26.0" × 10.0"
- 245/35R18lower profile: 24.8" × 9.6"
- 245/45R18taller sidewall: 26.7" × 9.6"
Compare 245/40R18 with another size
Questions
- How tall is a 245/40R18 tire?
- A 245/40R18 tire is 25.7 inches tall (653 mm), calculated from the size. It is 9.6 inches wide with 3.9 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 245/40R18 mean?
- 245/40R18 means a tire 245 mm wide, with sidewalls 40% as tall as the tire is wide (98 mm), radial construction (R), for a 18 inch wheel.
- How many revolutions per mile does a 245/40R18 tire make?
- About 784 revolutions per mile, based on a circumference of 80.8 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 245/40R18 tire?
- Roughly 8.0" to 9.5". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 195/50R18 instead of 245/40R18?
- 195/50R18 is −0.04 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.