305/50R18 tire size in inches
A 305/50R18 tire measures
30.0" tall × 12.0" wide
6.00" sidewall on a 18" wheel. 672 revolutions per mile.
305/50R18 means a tire 305 mm wide, with sidewalls 50% as tall as the tire is wide (153 mm), radial construction (R), for a 18 inch wheel.
305/50R18 specs
| Overall diameter (height) | 30.01 inches (762 mm) |
|---|---|
| Section width | 12.01 inches (305 mm) |
| Sidewall height | 6.00 inches (153 mm) |
| Wheel (rim) diameter | 18 inches |
| Circumference | 94.3 inches (2,395 mm) |
| Revolutions per mile | 672 |
| Revolutions per kilometer | 418 |
| Approximate rim width | 9.0" to 10.5" |
| In inches (flotation style) | 30.0x12.0R18 |
| Aspect ratio | 50% |
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 305/50R18 on a 18" wheel
These 18" sizes are within 3% of 305/50R18's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 235/65R18 | 30.03" | 9.25" | +0.1% | 60.0 mph | Compare |
| 255/60R18 | 30.05" | 10.04" | +0.1% | 60.1 mph | Compare |
| 275/55R18 | 29.91" | 10.83" | −0.3% | 59.8 mph | Compare |
| 205/75R18 | 30.11" | 8.07" | +0.3% | 60.2 mph | Compare |
| 335/45R18 | 29.87" | 13.19" | −0.5% | 59.7 mph | Compare |
| 215/70R18 | 29.85" | 8.46" | −0.5% | 59.7 mph | Compare |
| 285/55R18 | 30.34" | 11.22" | +1.1% | 60.7 mph | Compare |
| 295/50R18 | 29.61" | 11.61" | −1.3% | 59.2 mph | Compare |
| 225/70R18 | 30.40" | 8.86" | +1.3% | 60.8 mph | Compare |
| 315/50R18 | 30.40" | 12.40" | +1.3% | 60.8 mph | Compare |
| 245/60R18 | 29.57" | 9.65" | −1.4% | 59.1 mph | Compare |
| 195/75R18 | 29.52" | 7.68" | −1.6% | 59.0 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 215/65R19 | 19" | 30.00" | 0.0% | Compare |
| 305/25R24 | 24" | 30.00" | 0.0% | Compare |
| 30x9.50R15 | 15" | 30.00" | 0.0% | Compare |
| 275/60R17 | 17" | 29.99" | −0.1% | Compare |
| 255/30R24 | 24" | 30.02" | +0.1% | Compare |
| 255/40R22 | 22" | 30.03" | +0.1% | Compare |
| 255/45R21 | 21" | 30.04" | +0.1% | Compare |
| 255/50R20 | 20" | 30.04" | +0.1% | Compare |
| 285/40R21 | 21" | 29.98" | −0.1% | Compare |
| 255/55R19 | 19" | 30.04" | +0.1% | Compare |
| 255/65R17 | 17" | 30.05" | +0.1% | Compare |
| 255/70R16 | 16" | 30.06" | +0.2% | Compare |
One size up or down
- 295/50R18narrower: 29.6" × 11.6"
- 315/50R18wider: 30.4" × 12.4"
- 305/45R18lower profile: 28.8" × 12.0"
- 305/55R18taller sidewall: 31.2" × 12.0"
Compare 305/50R18 with another size
Questions
- How tall is a 305/50R18 tire?
- A 305/50R18 tire is 30.0 inches tall (762 mm), calculated from the size. It is 12.0 inches wide with 6.0 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 305/50R18 mean?
- 305/50R18 means a tire 305 mm wide, with sidewalls 50% as tall as the tire is wide (153 mm), radial construction (R), for a 18 inch wheel.
- How many revolutions per mile does a 305/50R18 tire make?
- About 672 revolutions per mile, based on a circumference of 94.3 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 305/50R18 tire?
- Roughly 9.0" to 10.5". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 235/65R18 instead of 305/50R18?
- 235/65R18 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.