275/55R18 tire size
275/55R18 is a metric size: 29.9" tall, 10.8" wide, on a 18" rim — about a 30x11.00R18. The sidewall is 6.0" and the tire turns 674 times per mile.
275/55R18 specs
| Overall diameter (height) | 29.91" · 760 mm |
|---|---|
| Section width | 10.83" · 275 mm |
| Sidewall height | 5.95" · 151 mm (55% of width) |
| Rim diameter | 18" |
| Circumference | 93.96" · 2.387 m |
| Revolutions per mile | 674 (419 per km) |
| Inch (flotation) equivalent | 30x11.00R18 |
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" | -2.70% | -40 mm | 58.4 mph | calculate → |
| 265/60R18 common | 30.52" | +2.04% | -10 mm | 61.2 mph | calculate → |
| 225/60R18 common | 28.63" | -4.28% | -50 mm | 57.4 mph | calculate → |
| 245/60R18 common | 29.57" | -1.12% | -30 mm | 59.3 mph | calculate → |
| 255/55R18 common | 29.04" | -2.90% | -20 mm | 58.3 mph | calculate → |
| 235/65R18 common | 30.03" | +0.39% | -40 mm | 60.2 mph | calculate → |
| 255/65R18 common | 31.05" | +3.82% | -20 mm | 62.3 mph | calculate → |
| 255/60R18 | 30.05" | +0.46% | -20 mm | 60.3 mph | calculate → |
| 245/55R18 | 28.61" | -4.34% | -30 mm | 57.4 mph | calculate → |
| 275/60R18 | 30.99" | +3.62% | 0 mm | 62.2 mph | calculate → |
| 295/45R18 | 28.45" | -4.87% | +20 mm | 57.1 mph | calculate → |
| 155/90R18 | 28.98" | -3.09% | -120 mm | 58.1 mph | calculate → |
| 165/90R18 | 29.69" | -0.72% | -110 mm | 59.6 mph | calculate → |
| 285/50R18 | 29.22" | -2.30% | +10 mm | 58.6 mph | calculate → |
| 305/45R18 | 28.81" | -3.69% | +30 mm | 57.8 mph | calculate → |
| 325/45R18 | 29.52" | -1.32% | +50 mm | 59.2 mph | calculate → |
| 285/55R18 | 30.34" | +1.45% | +10 mm | 60.9 mph | calculate → |
| 175/90R18 | 30.40" | +1.65% | -100 mm | 61.0 mph | calculate → |
| 245/65R18 | 30.54" | +2.11% | -30 mm | 61.3 mph | calculate → |
| 235/70R18 | 30.95" | +3.49% | -40 mm | 62.1 mph | calculate → |
| 225/65R18 | 29.52" | -1.32% | -50 mm | 59.2 mph | calculate → |
| 265/55R18 | 29.48" | -1.45% | -10 mm | 59.1 mph | calculate → |
| 265/50R18 | 28.43" | -4.94% | -10 mm | 57.0 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 | |
|---|---|---|---|---|---|
| 255/55R19 common | 30.04" | +0.45% | -20 mm | 60.3 mph | calculate → |
| 255/65R17 common | 30.05" | +0.47% | -20 mm | 60.3 mph | calculate → |
| 235/70R17 | 29.95" | +0.14% | -40 mm | 60.1 mph | calculate → |
| 275/50R19 | 29.83" | -0.28% | 0 mm | 59.8 mph | calculate → |
| 275/60R17 | 29.99" | +0.28% | 0 mm | 60.2 mph | calculate → |
| 235/60R19 | 30.10" | +0.64% | -40 mm | 60.4 mph | calculate → |
| 175/80R19 | 30.02" | +0.38% | -100 mm | 60.2 mph | calculate → |
Try another size against 275/55R18
Questions
What size is 275/55R18 in inches?
275/55R18 is about 29.9" tall and 10.8" wide on a 18-inch rim — roughly a 30x11.00R18 in inch sizing.
What does 275/55R18 mean?
275 mm section width, sidewall 55% of the width (5.95"), radial construction, 18-inch rim.
What tire sizes are equivalent to 275/55R18?
On the same 18" rim, within 3% of the diameter: 235/65R18 (+0.39%), 255/60R18 (+0.46%), 165/90R18 (-0.72%), 245/60R18 (-1.12%), 225/65R18 (-1.32%), 325/45R18 (-1.32%).
How many revolutions per mile does a 275/55R18 tire make?
About 674 revolutions per mile (circumference 94.0").
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.