255/50R20 tire size
255/50R20 is a metric size: 30.0" tall, 10.0" wide, on a 20" rim — about a 30x10.00R20. The sidewall is 5.0" and the tire turns 671 times per mile.
255/50R20 specs
| Overall diameter (height) | 30.04" · 763 mm |
|---|---|
| Section width | 10.04" · 255 mm |
| Sidewall height | 5.02" · 127 mm (50% of width) |
| Rim diameter | 20" |
| Circumference | 94.37" · 2.397 m |
| Revolutions per mile | 671 (417 per km) |
| Inch (flotation) equivalent | 30x10.00R20 |
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 | |
|---|---|---|---|---|---|
| 245/45R20 common | 28.68" | -4.52% | -10 mm | 57.3 mph | compare → |
| 255/45R20 common | 29.04" | -3.34% | 0 mm | 58.0 mph | compare → |
| 275/40R20 common | 28.66" | -4.59% | +20 mm | 57.2 mph | compare → |
| 265/50R20 common | 30.43" | +1.31% | +10 mm | 60.8 mph | compare → |
| 245/50R20 common | 29.65" | -1.31% | -10 mm | 59.2 mph | compare → |
| 275/45R20 common | 29.74" | -0.98% | +20 mm | 59.4 mph | compare → |
| 255/55R20 common | 31.04" | +3.34% | 0 mm | 62.0 mph | compare → |
| 235/55R20 common | 30.18" | +0.46% | -20 mm | 60.3 mph | compare → |
| 265/45R20 common | 29.39" | -2.16% | +10 mm | 58.7 mph | compare → |
| 315/35R20 common | 28.68" | -4.52% | +60 mm | 57.3 mph | compare → |
| 275/50R20 common | 30.83" | +2.62% | +20 mm | 61.6 mph | compare → |
| 295/40R20 | 29.29" | -2.49% | +40 mm | 58.5 mph | compare → |
| 285/50R20 | 31.22" | +3.93% | +30 mm | 62.4 mph | compare → |
| 285/40R20 | 28.98" | -3.54% | +30 mm | 57.9 mph | compare → |
| 235/50R20 | 29.25" | -2.62% | -20 mm | 58.4 mph | compare → |
| 285/45R20 | 30.10" | +0.20% | +30 mm | 60.1 mph | compare → |
| 295/45R20 | 30.45" | +1.38% | +40 mm | 60.8 mph | compare → |
| 305/40R20 | 29.61" | -1.44% | +50 mm | 59.1 mph | compare → |
| 235/60R20 | 31.10" | +3.54% | -20 mm | 62.1 mph | calculate → |
| 325/35R20 | 28.96" | -3.60% | +70 mm | 57.8 mph | calculate → |
| 305/45R20 | 30.81" | +2.56% | +50 mm | 61.5 mph | calculate → |
| 31x18.00R20 | 31.00" | +3.20% | +202 mm | 61.9 mph | calculate → |
| 29x15.00R20 | 29.00" | -3.46% | +126 mm | 57.9 mph | calculate → |
| 29x18.00R20 | 29.00" | -3.46% | +202 mm | 57.9 mph | calculate → |
| 265/55R20 | 31.48" | +4.78% | +10 mm | 62.9 mph | calculate → |
| 175/70R20 | 29.65" | -1.31% | -80 mm | 59.2 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 | |
|---|---|---|---|---|---|
| 255/55R19 common | 30.04" | +0.01% | 0 mm | 60.0 mph | compare → |
| 295/40R21 | 30.29" | +0.84% | +40 mm | 60.5 mph | compare → |
| 285/40R21 | 29.98" | -0.21% | +30 mm | 59.9 mph | compare → |
| 255/45R21 | 30.04" | -0.01% | 0 mm | 60.0 mph | compare → |
| 275/50R19 | 29.83" | -0.71% | +20 mm | 59.6 mph | compare → |
| 235/50R21 | 30.25" | +0.71% | -20 mm | 60.4 mph | calculate → |
| 235/60R19 | 30.10" | +0.21% | -20 mm | 60.1 mph | calculate → |
| 175/80R19 | 30.02" | -0.05% | -80 mm | 60.0 mph | calculate → |
Try another size against 255/50R20
Questions
What size is 255/50R20 in inches?
255/50R20 is about 30.0" tall and 10.0" wide on a 20-inch rim — roughly a 30x10.00R20 in inch sizing.
What does 255/50R20 mean?
255 mm section width, sidewall 50% of the width (5.02"), radial construction, 20-inch rim.
What tire sizes are equivalent to 255/50R20?
On the same 20" rim, within 3% of the diameter: 285/45R20 (+0.20%), 235/55R20 (+0.46%), 275/45R20 (-0.98%), 175/70R20 (-1.31%), 245/50R20 (-1.31%), 265/50R20 (+1.31%).
How many revolutions per mile does a 255/50R20 tire make?
About 671 revolutions per mile (circumference 94.4").
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.