255/55R20 tire size
255/55R20 is a metric size: 31.0" tall, 10.0" wide, on a 20" rim — about a 31x10.00R20. The sidewall is 5.5" and the tire turns 650 times per mile.
255/55R20 specs
| Overall diameter (height) | 31.04" · 789 mm |
|---|---|
| Section width | 10.04" · 255 mm |
| Sidewall height | 5.52" · 140 mm (55% of width) |
| Rim diameter | 20" |
| Circumference | 97.53" · 2.477 m |
| Revolutions per mile | 650 (404 per km) |
| Inch (flotation) equivalent | 31x10.00R20 |
Equivalent sizes on a 20" 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 | |
|---|---|---|---|---|---|
| 275/55R20 common | 31.91" | +2.79% | +20 mm | 61.7 mph | compare → |
| 255/50R20 common | 30.04" | -3.23% | 0 mm | 58.1 mph | compare → |
| 265/50R20 common | 30.43" | -1.97% | +10 mm | 58.8 mph | compare → |
| 245/50R20 common | 29.65" | -4.50% | -10 mm | 57.3 mph | compare → |
| 275/45R20 common | 29.74" | -4.19% | +20 mm | 57.5 mph | compare → |
| 235/55R20 common | 30.18" | -2.79% | -20 mm | 58.3 mph | compare → |
| 265/60R20 common | 32.52" | +4.76% | +10 mm | 62.9 mph | compare → |
| 285/55R20 common | 32.34" | +4.19% | +30 mm | 62.5 mph | compare → |
| 275/50R20 common | 30.83" | -0.70% | +20 mm | 59.6 mph | compare → |
| 285/50R20 | 31.22" | +0.57% | +30 mm | 60.3 mph | compare → |
| 245/60R20 | 31.57" | +1.71% | -10 mm | 61.0 mph | compare → |
| 285/45R20 | 30.10" | -3.04% | +30 mm | 58.2 mph | compare → |
| 305/50R20 | 32.01" | +3.11% | +50 mm | 61.9 mph | compare → |
| 295/45R20 | 30.45" | -1.90% | +40 mm | 58.9 mph | compare → |
| 305/40R20 | 29.61" | -4.63% | +50 mm | 57.2 mph | compare → |
| 255/60R20 | 32.05" | +3.23% | 0 mm | 61.9 mph | compare → |
| 235/60R20 | 31.10" | +0.19% | -20 mm | 60.1 mph | calculate → |
| 31x18.00R20 | 31.00" | -0.14% | +202 mm | 59.9 mph | calculate → |
| 305/45R20 | 30.81" | -0.76% | +50 mm | 59.5 mph | calculate → |
| 265/55R20 | 31.48" | +1.40% | +10 mm | 60.8 mph | calculate → |
| 295/50R20 | 31.61" | +1.84% | +40 mm | 61.1 mph | calculate → |
| 315/50R20 | 32.40" | +4.38% | +60 mm | 62.6 mph | calculate → |
| 175/70R20 | 29.65" | -4.50% | -80 mm | 57.3 mph | calculate → |
Plus / minus sizing: 19" and 21" rims
Same overall height on a different rim. Check wheel width and clearance before switching.
| Size | Diameter | Difference | Width | Speedo at 60 | |
|---|---|---|---|---|---|
| 255/60R19 common | 31.05" | +0.01% | 0 mm | 60.0 mph | compare → |
| 275/45R21 | 30.74" | -0.96% | +20 mm | 59.4 mph | compare → |
| 285/45R21 | 31.10" | +0.18% | +30 mm | 60.1 mph | compare → |
| 275/55R19 | 30.91" | -0.43% | +20 mm | 59.7 mph | compare → |
| 315/40R21 | 30.92" | -0.39% | +60 mm | 59.8 mph | compare → |
| 255/50R21 | 31.04" | -0.01% | 0 mm | 60.0 mph | compare → |
| 235/65R19 | 31.03" | -0.05% | -20 mm | 60.0 mph | calculate → |
| 325/40R21 | 31.24" | +0.62% | +70 mm | 60.4 mph | calculate → |
Try another size against 255/55R20
Questions
What size is 255/55R20 in inches?
255/55R20 is about 31.0" tall and 10.0" wide on a 20-inch rim — roughly a 31x10.00R20 in inch sizing.
What does 255/55R20 mean?
255 mm section width, sidewall 55% of the width (5.52"), radial construction, 20-inch rim.
What tire sizes are equivalent to 255/55R20?
On the same 20" rim, within 3% of the diameter: 31x18.00R20 (-0.14%), 235/60R20 (+0.19%), 285/50R20 (+0.57%), 275/50R20 (-0.70%), 305/45R20 (-0.76%), 265/55R20 (+1.40%).
How many revolutions per mile does a 255/55R20 tire make?
About 650 revolutions per mile (circumference 97.5").
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.