325/55R18 tire size in inches
A 325/55R18 tire measures
32.1" tall × 12.8" wide
7.04" sidewall on a 18" wheel. 629 revolutions per mile.
325/55R18 means a tire 325 mm wide, with sidewalls 55% as tall as the tire is wide (179 mm), radial construction (R), for a 18 inch wheel.
325/55R18 specs
| Overall diameter (height) | 32.07 inches (815 mm) |
|---|---|
| Section width | 12.80 inches (325 mm) |
| Sidewall height | 7.04 inches (179 mm) |
| Wheel (rim) diameter | 18 inches |
| Circumference | 100.8 inches (2,559 mm) |
| Revolutions per mile | 629 |
| Revolutions per kilometer | 391 |
| Approximate rim width | 9.5" to 11.0" |
| In inches (flotation style) | 32.1x12.8R18 |
| Aspect ratio | 55% |
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 325/55R18 on a 18" wheel
These 18" sizes are within 3% of 325/55R18's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 275/65R18 | 32.07" | 10.83" | 0.0% | 60.0 mph | Compare |
| 255/70R18 | 32.06" | 10.04" | −0.1% | 60.0 mph | Compare |
| 295/60R18 | 31.94" | 11.61" | −0.4% | 59.7 mph | Compare |
| 235/75R18 | 31.88" | 9.25" | −0.6% | 59.6 mph | Compare |
| 305/60R18 | 32.41" | 12.01" | +1.0% | 60.6 mph | Compare |
| 245/75R18 | 32.47" | 9.65" | +1.2% | 60.7 mph | Compare |
| 315/55R18 | 31.64" | 12.40" | −1.4% | 59.2 mph | Compare |
| 335/55R18 | 32.51" | 13.19" | +1.4% | 60.8 mph | Compare |
| 265/65R18 | 31.56" | 10.43" | −1.6% | 59.0 mph | Compare |
| 285/65R18 | 32.59" | 11.22" | +1.6% | 61.0 mph | Compare |
| 265/70R18 | 32.61" | 10.43" | +1.7% | 61.0 mph | Compare |
| 245/70R18 | 31.50" | 9.65" | −1.8% | 58.9 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 255/85R15 | 15" | 32.07" | 0.0% | Compare |
| 255/80R16 | 16" | 32.06" | 0.0% | Compare |
| 255/75R17 | 17" | 32.06" | 0.0% | Compare |
| 255/65R19 | 19" | 32.05" | −0.1% | Compare |
| 285/45R22 | 22" | 32.10" | +0.1% | Compare |
| 295/65R17 | 17" | 32.10" | +0.1% | Compare |
| 255/60R20 | 20" | 32.05" | −0.1% | Compare |
| 255/55R21 | 21" | 32.04" | −0.1% | Compare |
| 255/50R22 | 22" | 32.04" | −0.1% | Compare |
| 255/40R24 | 24" | 32.03" | −0.1% | Compare |
| 235/65R20 | 20" | 32.03" | −0.1% | Compare |
| 295/35R24 | 24" | 32.13" | +0.2% | Compare |
One size up or down
- 315/55R18narrower: 31.6" × 12.4"
- 335/55R18wider: 32.5" × 13.2"
- 325/50R18lower profile: 30.8" × 12.8"
- 325/60R18taller sidewall: 33.4" × 12.8"
Compare 325/55R18 with another size
Questions
- How tall is a 325/55R18 tire?
- A 325/55R18 tire is 32.1 inches tall (815 mm), calculated from the size. It is 12.8 inches wide with 7.0 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 325/55R18 mean?
- 325/55R18 means a tire 325 mm wide, with sidewalls 55% as tall as the tire is wide (179 mm), radial construction (R), for a 18 inch wheel.
- How many revolutions per mile does a 325/55R18 tire make?
- About 629 revolutions per mile, based on a circumference of 100.8 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 325/55R18 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 275/65R18 instead of 325/55R18?
- 275/65R18 is 0.00 inches (0.0%) 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.