225/55R18 tire size
225/55R18 is a metric size: 27.7" tall, 8.9" wide, on a 18" rim — about a 27.5x9.00R18. The sidewall is 4.9" and the tire turns 727 times per mile.
225/55R18 specs
| Overall diameter (height) | 27.74" · 705 mm |
|---|---|
| Section width | 8.86" · 225 mm |
| Sidewall height | 4.87" · 124 mm (55% of width) |
| Rim diameter | 18" |
| Circumference | 87.16" · 2.214 m |
| Revolutions per mile | 727 (452 per km) |
| Inch (flotation) equivalent | 27.5x9.00R18 |
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" | +4.90% | +10 mm | 62.9 mph | compare → |
| 245/45R18 common | 26.68" | -3.83% | +20 mm | 57.7 mph | compare → |
| 235/50R18 common | 27.25" | -1.77% | +10 mm | 58.9 mph | compare → |
| 235/55R18 common | 28.18" | +1.56% | +10 mm | 60.9 mph | compare → |
| 225/60R18 common | 28.63" | +3.19% | 0 mm | 61.9 mph | compare → |
| 225/50R18 common | 26.86" | -3.19% | 0 mm | 58.1 mph | compare → |
| 255/55R18 common | 29.04" | +4.68% | +30 mm | 62.8 mph | compare → |
| 245/50R18 common | 27.65" | -0.35% | +20 mm | 59.8 mph | compare → |
| 255/45R18 common | 27.04" | -2.55% | +30 mm | 58.5 mph | compare → |
| 215/55R18 common | 27.31" | -1.56% | -10 mm | 59.1 mph | compare → |
| 275/40R18 common | 26.66" | -3.90% | +50 mm | 57.7 mph | compare → |
| 245/55R18 | 28.61" | +3.12% | +20 mm | 61.9 mph | compare → |
| 275/45R18 | 27.74" | 0.00% | +50 mm | 60.0 mph | compare → |
| 215/50R18 | 26.46" | -4.61% | -10 mm | 57.2 mph | compare → |
| 265/45R18 | 27.39" | -1.28% | +40 mm | 59.2 mph | compare → |
| 295/40R18 | 27.29" | -1.63% | +70 mm | 59.0 mph | compare → |
| 285/40R18 | 26.98" | -2.77% | +60 mm | 58.3 mph | calculate → |
| 345/35R18 | 27.51" | -0.85% | +120 mm | 59.5 mph | calculate → |
| 305/35R18 | 26.41" | -4.82% | +80 mm | 57.1 mph | calculate → |
| 295/45R18 | 28.45" | +2.55% | +70 mm | 61.5 mph | calculate → |
| 255/50R18 | 28.04" | +1.06% | +30 mm | 60.6 mph | calculate → |
| 315/40R18 | 27.92" | +0.64% | +90 mm | 60.4 mph | calculate → |
| 155/90R18 | 28.98" | +4.47% | -70 mm | 62.7 mph | calculate → |
| 305/40R18 | 27.61" | -0.50% | +80 mm | 59.7 mph | calculate → |
| 215/60R18 | 28.16" | +1.49% | -10 mm | 60.9 mph | calculate → |
| 155/85R18 | 28.37" | +2.27% | -70 mm | 61.4 mph | calculate → |
| 305/45R18 | 28.81" | +3.83% | +80 mm | 62.3 mph | calculate → |
| 145/85R18 | 27.70" | -0.14% | -80 mm | 59.9 mph | calculate → |
| 28x12.00R18 | 28.00" | +0.92% | +80 mm | 60.6 mph | calculate → |
| 285/45R18 | 28.10" | +1.28% | +60 mm | 60.8 mph | calculate → |
| 145/80R18 | 27.13" | -2.20% | -80 mm | 58.7 mph | calculate → |
| 165/70R18 | 27.09" | -2.34% | -60 mm | 58.6 mph | calculate → |
| 325/35R18 | 26.96" | -2.84% | +100 mm | 58.3 mph | calculate → |
| 155/70R18 | 26.54" | -4.33% | -70 mm | 57.4 mph | calculate → |
| 205/60R18 | 27.69" | -0.21% | -20 mm | 59.9 mph | calculate → |
| 28x10.00R18 | 28.00" | +0.92% | +29 mm | 60.6 mph | calculate → |
| 195/60R18 | 27.21" | -1.92% | -30 mm | 58.9 mph | calculate → |
| 265/50R18 | 28.43" | +2.48% | +40 mm | 61.5 mph | calculate → |
| 315/35R18 | 26.68" | -3.83% | +90 mm | 57.7 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 | |
|---|---|---|---|---|---|
| 245/45R19 common | 27.68" | -0.23% | +20 mm | 59.9 mph | compare → |
| 225/60R17 common | 27.63" | -0.41% | 0 mm | 59.8 mph | compare → |
| 275/40R19 common | 27.66" | -0.30% | +50 mm | 59.8 mph | compare → |
| 215/65R17 common | 28.00" | +0.94% | -10 mm | 60.6 mph | compare → |
| 285/40R19 | 27.98" | +0.84% | +60 mm | 60.5 mph | compare → |
| 245/55R17 | 27.61" | -0.48% | +20 mm | 59.7 mph | calculate → |
| 155/70R19 | 27.54" | -0.72% | -70 mm | 59.6 mph | calculate → |
| 305/45R17 | 27.81" | +0.23% | +80 mm | 60.1 mph | calculate → |
| 155/90R17 | 27.98" | +0.87% | -70 mm | 60.5 mph | calculate → |
| 315/35R19 | 27.68" | -0.23% | +90 mm | 59.9 mph | calculate → |
| 275/50R17 | 27.83" | +0.30% | +50 mm | 60.2 mph | calculate → |
| 28x6.00R17 | 28.00" | +0.92% | -73 mm | 60.6 mph | calculate → |
| 225/50R19 | 27.86" | +0.41% | 0 mm | 60.2 mph | calculate → |
| 345/40R17 | 27.87" | +0.44% | +120 mm | 60.3 mph | calculate → |
| 205/65R17 | 27.49" | -0.91% | -20 mm | 59.5 mph | calculate → |
Try another size against 225/55R18
Questions
What size is 225/55R18 in inches?
225/55R18 is about 27.7" tall and 8.9" wide on a 18-inch rim — roughly a 27.5x9.00R18 in inch sizing.
What does 225/55R18 mean?
225 mm section width, sidewall 55% of the width (4.87"), radial construction, 18-inch rim.
What tire sizes are equivalent to 225/55R18?
On the same 18" rim, within 3% of the diameter: 275/45R18 (0.00%), 145/85R18 (-0.14%), 205/60R18 (-0.21%), 245/50R18 (-0.35%), 305/40R18 (-0.50%), 315/40R18 (+0.64%).
How many revolutions per mile does a 225/55R18 tire make?
About 727 revolutions per mile (circumference 87.2").
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.