285/55R18 tire size
285/55R18 is a metric size: 30.3" tall, 11.2" wide, on a 18" rim — about a 30.5x11.00R18. The sidewall is 6.2" and the tire turns 665 times per mile.
285/55R18 specs
| Overall diameter (height) | 30.34" · 771 mm |
|---|---|
| Section width | 11.22" · 285 mm |
| Sidewall height | 6.17" · 157 mm (55% of width) |
| Rim diameter | 18" |
| Circumference | 95.32" · 2.421 m |
| Revolutions per mile | 665 (413 per km) |
| Inch (flotation) equivalent | 30.5x11.00R18 |
Equivalent sizes on a 18" rim
Sizes within ±5% of the overall diameter. Green rows are inside the usual ±3% limit for keeping the speedometer, ABS and gearing right; red rows are bigger changes that need clearance checks.
| Size | Diameter | Difference | Width | Speedo at 60 | |
|---|---|---|---|---|---|
| 235/60R18 common | 29.10" | -4.09% | -50 mm | 57.5 mph | calculate → |
| 265/60R18 common | 30.52" | +0.58% | -20 mm | 60.4 mph | calculate → |
| 245/60R18 common | 29.57" | -2.53% | -40 mm | 58.5 mph | calculate → |
| 255/55R18 common | 29.04" | -4.28% | -30 mm | 57.4 mph | calculate → |
| 265/65R18 common | 31.56" | +4.02% | -20 mm | 62.4 mph | calculate → |
| 235/65R18 common | 30.03" | -1.04% | -50 mm | 59.4 mph | calculate → |
| 255/65R18 common | 31.05" | +2.34% | -30 mm | 61.4 mph | calculate → |
| 255/60R18 | 30.05" | -0.97% | -30 mm | 59.4 mph | calculate → |
| 285/60R18 | 31.46" | +3.70% | 0 mm | 62.2 mph | calculate → |
| 275/60R18 | 30.99" | +2.14% | -10 mm | 61.3 mph | calculate → |
| 155/90R18 | 28.98" | -4.48% | -130 mm | 57.3 mph | calculate → |
| 165/90R18 | 29.69" | -2.14% | -120 mm | 58.7 mph | calculate → |
| 285/50R18 | 29.22" | -3.70% | 0 mm | 57.8 mph | calculate → |
| 245/70R18 | 31.50" | +3.83% | -40 mm | 62.3 mph | calculate → |
| 175/90R18 | 30.40" | +0.19% | -110 mm | 60.1 mph | calculate → |
| 245/65R18 | 30.54" | +0.65% | -40 mm | 60.4 mph | calculate → |
| 275/55R18 | 29.91" | -1.43% | -10 mm | 59.1 mph | calculate → |
| 235/70R18 | 30.95" | +2.01% | -50 mm | 61.2 mph | calculate → |
| 325/45R18 | 29.52" | -2.72% | +40 mm | 58.4 mph | calculate → |
| 225/65R18 | 29.52" | -2.72% | -60 mm | 58.4 mph | calculate → |
| 265/55R18 | 29.48" | -2.85% | -20 mm | 58.3 mph | calculate → |
Plus / minus sizing: 17" and 19" rims
Same overall height on a different rim. Check wheel width and clearance before switching.
| Size | Diameter | Difference | Width | Speedo at 60 | |
|---|---|---|---|---|---|
| 245/70R17 common | 30.50" | +0.53% | -40 mm | 60.3 mph | calculate → |
| 265/65R17 common | 30.56" | +0.73% | -20 mm | 60.4 mph | calculate → |
| 255/55R19 common | 30.04" | -0.99% | -30 mm | 59.4 mph | calculate → |
| 255/65R17 common | 30.05" | -0.96% | -30 mm | 59.4 mph | calculate → |
| 265/55R19 | 30.48" | +0.44% | -20 mm | 60.3 mph | calculate → |
| 225/75R17 | 30.29" | -0.18% | -60 mm | 59.9 mph | calculate → |
| 235/60R19 | 30.10" | -0.79% | -50 mm | 59.5 mph | calculate → |
| 315/55R17 | 30.64" | +0.99% | +30 mm | 60.6 mph | calculate → |
| 285/60R17 | 30.46" | +0.40% | 0 mm | 60.2 mph | calculate → |
Try another size against 285/55R18
Questions
What size is 285/55R18 in inches?
285/55R18 is about 30.3" tall and 11.2" wide on a 18-inch rim — roughly a 30.5x11.00R18 in inch sizing.
What does 285/55R18 mean?
285 mm section width, sidewall 55% of the width (6.17"), radial construction, 18-inch rim.
What tire sizes are equivalent to 285/55R18?
On the same 18" rim, within 3% of the diameter: 175/90R18 (+0.19%), 265/60R18 (+0.58%), 245/65R18 (+0.65%), 255/60R18 (-0.97%), 235/65R18 (-1.04%), 275/55R18 (-1.43%).
How many revolutions per mile does a 285/55R18 tire make?
About 665 revolutions per mile (circumference 95.3").
How these numbers are computed
Diameter = rim + 2 × sidewall, sidewall = width × aspect ÷ 100, circumference = π × diameter, revolutions per mile = 63,360 ÷ circumference. Real tires differ by brand by a few tenths of an inch. Last reviewed October 14, 2026.