225/75R18 tire size in inches
A 225/75R18 tire measures
31.3" tall × 8.9" wide
6.64" sidewall on a 18" wheel. 645 revolutions per mile.
225/75R18 means a tire 225 mm wide, with sidewalls 75% as tall as the tire is wide (169 mm), radial construction (R), for a 18 inch wheel.
225/75R18 specs
| Overall diameter (height) | 31.29 inches (795 mm) |
|---|---|
| Section width | 8.86 inches (225 mm) |
| Sidewall height | 6.64 inches (169 mm) |
| Wheel (rim) diameter | 18 inches |
| Circumference | 98.3 inches (2,497 mm) |
| Revolutions per mile | 645 |
| Revolutions per kilometer | 401 |
| Approximate rim width | 6.0" to 7.5" |
| In inches (flotation style) | 31.3x8.9R18 |
| Aspect ratio | 75% |
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 225/75R18 on a 18" wheel
These 18" sizes are within 3% of 225/75R18's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 305/55R18 | 31.21" | 12.01" | −0.3% | 59.8 mph | Compare |
| 335/50R18 | 31.19" | 13.19" | −0.3% | 59.8 mph | Compare |
| 285/60R18 | 31.46" | 11.22" | +0.6% | 60.3 mph | Compare |
| 245/70R18 | 31.50" | 9.65" | +0.7% | 60.4 mph | Compare |
| 255/65R18 | 31.05" | 10.04" | −0.8% | 59.5 mph | Compare |
| 265/65R18 | 31.56" | 10.43" | +0.9% | 60.5 mph | Compare |
| 275/60R18 | 30.99" | 10.83" | −0.9% | 59.4 mph | Compare |
| 235/70R18 | 30.95" | 9.25" | −1.1% | 59.4 mph | Compare |
| 315/55R18 | 31.64" | 12.40" | +1.1% | 60.7 mph | Compare |
| 325/50R18 | 30.80" | 12.80" | −1.6% | 59.1 mph | Compare |
| 295/55R18 | 30.78" | 11.61" | −1.6% | 59.0 mph | Compare |
| 215/75R18 | 30.70" | 8.46" | −1.9% | 58.9 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 295/40R22 | 22" | 31.29" | 0.0% | Compare |
| 265/35R24 | 24" | 31.30" | +0.1% | Compare |
| 235/50R22 | 22" | 31.25" | −0.1% | Compare |
| 275/75R15 | 15" | 31.24" | −0.2% | Compare |
| 325/40R21 | 21" | 31.24" | −0.2% | Compare |
| 335/35R22 | 22" | 31.23" | −0.2% | Compare |
| 285/55R19 | 19" | 31.34" | +0.2% | Compare |
| 345/45R19 | 19" | 31.22" | −0.2% | Compare |
| 285/50R20 | 20" | 31.22" | −0.2% | Compare |
| 305/30R24 | 24" | 31.20" | −0.3% | Compare |
| 265/45R22 | 22" | 31.39" | +0.3% | Compare |
| 355/40R20 | 20" | 31.18" | −0.3% | Compare |
One size up or down
Compare 225/75R18 with another size
Questions
- How tall is a 225/75R18 tire?
- A 225/75R18 tire is 31.3 inches tall (795 mm), calculated from the size. It is 8.9 inches wide with 6.6 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 225/75R18 mean?
- 225/75R18 means a tire 225 mm wide, with sidewalls 75% as tall as the tire is wide (169 mm), radial construction (R), for a 18 inch wheel.
- How many revolutions per mile does a 225/75R18 tire make?
- About 645 revolutions per mile, based on a circumference of 98.3 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 225/75R18 tire?
- Roughly 6.0" to 7.5". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 305/55R18 instead of 225/75R18?
- 305/55R18 is −0.08 inches (−0.3%) in overall diameter, so at an indicated 60 mph you would be doing 59.8 mph. Differences under 3% are usually fine, but check clearance, load index and your vehicle's placard.