255/55R18 tire size
255/55R18 is a metric size: 29.0" tall, 10.0" wide, on a 18" rim — about a 29x10.00R18. The sidewall is 5.5" and the tire turns 694 times per mile.
255/55R18 specs
| Overall diameter (height) | 29.04" · 738 mm |
|---|---|
| Section width | 10.04" · 255 mm |
| Sidewall height | 5.52" · 140 mm (55% of width) |
| Rim diameter | 18" |
| Circumference | 91.24" · 2.318 m |
| Revolutions per mile | 694 (431 per km) |
| Inch (flotation) equivalent | 29x10.00R18 |
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" | +0.20% | -20 mm | 60.1 mph | compare → |
| 235/55R18 common | 28.18" | -2.98% | -20 mm | 58.2 mph | compare → |
| 225/60R18 common | 28.63" | -1.42% | -30 mm | 59.1 mph | compare → |
| 245/60R18 common | 29.57" | +1.83% | -10 mm | 61.1 mph | compare → |
| 225/55R18 common | 27.74" | -4.47% | -30 mm | 57.3 mph | compare → |
| 235/65R18 common | 30.03" | +3.39% | -20 mm | 62.0 mph | compare → |
| 245/50R18 common | 27.65" | -4.81% | -10 mm | 57.1 mph | compare → |
| 255/60R18 | 30.05" | +3.46% | 0 mm | 62.1 mph | compare → |
| 245/55R18 | 28.61" | -1.49% | -10 mm | 59.1 mph | compare → |
| 275/45R18 | 27.74" | -4.47% | +20 mm | 57.3 mph | compare → |
| 295/45R18 | 28.45" | -2.03% | +40 mm | 58.8 mph | calculate → |
| 255/50R18 | 28.04" | -3.46% | 0 mm | 57.9 mph | calculate → |
| 155/90R18 | 28.98" | -0.20% | -100 mm | 59.9 mph | calculate → |
| 315/40R18 | 27.92" | -3.86% | +60 mm | 57.7 mph | calculate → |
| 285/50R18 | 29.22" | +0.61% | +30 mm | 60.4 mph | calculate → |
| 305/45R18 | 28.81" | -0.81% | +50 mm | 59.5 mph | calculate → |
| 165/90R18 | 29.69" | +2.24% | -90 mm | 61.3 mph | calculate → |
| 155/85R18 | 28.37" | -2.30% | -100 mm | 58.6 mph | calculate → |
| 215/60R18 | 28.16" | -3.05% | -40 mm | 58.2 mph | calculate → |
| 305/40R18 | 27.61" | -4.95% | +50 mm | 57.0 mph | calculate → |
| 325/45R18 | 29.52" | +1.63% | +70 mm | 61.0 mph | calculate → |
| 275/55R18 | 29.91" | +2.98% | +20 mm | 61.8 mph | calculate → |
| 285/45R18 | 28.10" | -3.25% | +30 mm | 58.0 mph | calculate → |
| 28x12.00R18 | 28.00" | -3.59% | +50 mm | 57.8 mph | calculate → |
| 285/55R18 | 30.34" | +4.47% | +30 mm | 62.7 mph | calculate → |
| 145/85R18 | 27.70" | -4.61% | -110 mm | 57.2 mph | calculate → |
| 175/90R18 | 30.40" | +4.68% | -80 mm | 62.8 mph | calculate → |
| 265/55R18 | 29.48" | +1.49% | +10 mm | 60.9 mph | calculate → |
| 225/65R18 | 29.52" | +1.63% | -30 mm | 61.0 mph | calculate → |
| 265/50R18 | 28.43" | -2.10% | +10 mm | 58.7 mph | calculate → |
| 28x10.00R18 | 28.00" | -3.59% | -1 mm | 57.8 mph | calculate → |
| 205/60R18 | 27.69" | -4.68% | -50 mm | 57.2 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 | |
|---|---|---|---|---|---|
| 235/55R19 common | 29.18" | +0.46% | -20 mm | 60.3 mph | compare → |
| 235/65R17 common | 29.03" | -0.05% | -20 mm | 60.0 mph | compare → |
| 255/50R19 common | 29.04" | -0.01% | 0 mm | 60.0 mph | compare → |
| 255/60R17 | 29.05" | +0.01% | 0 mm | 60.0 mph | compare → |
| 285/45R19 | 29.10" | +0.19% | +30 mm | 60.1 mph | compare → |
| 275/55R17 | 28.91" | -0.46% | +20 mm | 59.7 mph | compare → |
| 215/70R17 | 28.85" | -0.66% | -40 mm | 59.6 mph | calculate → |
| 315/40R19 | 28.92" | -0.42% | +60 mm | 59.7 mph | calculate → |
| 155/80R19 | 28.76" | -0.96% | -100 mm | 59.4 mph | calculate → |
Try another size against 255/55R18
Questions
What size is 255/55R18 in inches?
255/55R18 is about 29.0" tall and 10.0" wide on a 18-inch rim — roughly a 29x10.00R18 in inch sizing.
What does 255/55R18 mean?
255 mm section width, sidewall 55% of the width (5.52"), radial construction, 18-inch rim.
What tire sizes are equivalent to 255/55R18?
On the same 18" rim, within 3% of the diameter: 235/60R18 (+0.20%), 155/90R18 (-0.20%), 285/50R18 (+0.61%), 305/45R18 (-0.81%), 225/60R18 (-1.42%), 265/55R18 (+1.49%).
How many revolutions per mile does a 255/55R18 tire make?
About 694 revolutions per mile (circumference 91.2").
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.