255/45R20 tire size
255/45R20 is a metric size: 29.0" tall, 10.0" wide, on a 20" rim — about a 29x10.00R20. The sidewall is 4.5" and the tire turns 695 times per mile.
255/45R20 specs
| Overall diameter (height) | 29.04" · 737 mm |
|---|---|
| Section width | 10.04" · 255 mm |
| Sidewall height | 4.52" · 115 mm (45% of width) |
| Rim diameter | 20" |
| Circumference | 91.22" · 2.317 m |
| Revolutions per mile | 695 (432 per km) |
| Inch (flotation) equivalent | 29x10.00R20 |
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" | -1.22% | -10 mm | 59.3 mph | compare → |
| 275/40R20 common | 28.66" | -1.29% | +20 mm | 59.2 mph | compare → |
| 255/50R20 common | 30.04" | +3.46% | 0 mm | 62.1 mph | compare → |
| 245/40R20 common | 27.72" | -4.54% | -10 mm | 57.3 mph | compare → |
| 265/50R20 common | 30.43" | +4.81% | +10 mm | 62.9 mph | compare → |
| 245/50R20 common | 29.65" | +2.10% | -10 mm | 61.3 mph | compare → |
| 275/45R20 common | 29.74" | +2.44% | +20 mm | 61.5 mph | compare → |
| 235/55R20 common | 30.18" | +3.93% | -20 mm | 62.4 mph | compare → |
| 255/40R20 common | 28.03" | -3.46% | 0 mm | 57.9 mph | compare → |
| 265/45R20 common | 29.39" | +1.22% | +10 mm | 60.7 mph | compare → |
| 285/35R20 common | 27.85" | -4.07% | +30 mm | 57.6 mph | compare → |
| 315/35R20 common | 28.68" | -1.22% | +60 mm | 59.3 mph | compare → |
| 295/40R20 | 29.29" | +0.88% | +40 mm | 60.5 mph | compare → |
| 295/35R20 | 28.13" | -3.12% | +40 mm | 58.1 mph | compare → |
| 305/35R20 | 28.41" | -2.17% | +50 mm | 58.7 mph | compare → |
| 285/40R20 | 28.98" | -0.20% | +30 mm | 59.9 mph | compare → |
| 235/50R20 | 29.25" | +0.75% | -20 mm | 60.4 mph | compare → |
| 235/45R20 | 28.33" | -2.44% | -20 mm | 58.5 mph | compare → |
| 285/45R20 | 30.10" | +3.66% | +30 mm | 62.2 mph | compare → |
| 295/45R20 | 30.45" | +4.88% | +40 mm | 62.9 mph | compare → |
| 265/40R20 | 28.35" | -2.37% | +10 mm | 58.6 mph | compare → |
| 305/40R20 | 29.61" | +1.97% | +50 mm | 61.2 mph | compare → |
| 335/30R20 | 27.91" | -3.86% | +80 mm | 57.7 mph | calculate → |
| 325/30R20 | 27.68" | -4.68% | +70 mm | 57.2 mph | calculate → |
| 345/30R20 | 28.15" | -3.05% | +90 mm | 58.2 mph | calculate → |
| 215/45R20 | 27.62" | -4.88% | -40 mm | 57.1 mph | calculate → |
| 325/35R20 | 28.96" | -0.27% | +70 mm | 59.8 mph | calculate → |
| 195/50R20 | 27.68" | -4.68% | -60 mm | 57.2 mph | calculate → |
| 29x15.00R20 | 29.00" | -0.12% | +126 mm | 59.9 mph | calculate → |
| 29x18.00R20 | 29.00" | -0.12% | +202 mm | 59.9 mph | calculate → |
| 195/55R20 | 28.44" | -2.03% | -60 mm | 58.8 mph | calculate → |
| 175/70R20 | 29.65" | +2.10% | -80 mm | 61.3 mph | calculate → |
| 225/45R20 | 27.97" | -3.66% | -30 mm | 57.8 mph | calculate → |
| 155/65R20 | 27.93" | -3.80% | -100 mm | 57.7 mph | calculate → |
| 165/60R20 | 27.80" | -4.27% | -90 mm | 57.4 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 | |
|---|---|---|---|---|---|
| 235/55R19 common | 29.18" | +0.49% | -20 mm | 60.3 mph | compare → |
| 255/50R19 common | 29.04" | +0.01% | 0 mm | 60.0 mph | compare → |
| 295/35R21 | 29.13" | +0.33% | +40 mm | 60.2 mph | compare → |
| 255/40R21 | 29.03" | -0.01% | 0 mm | 60.0 mph | compare → |
| 285/35R21 | 28.85" | -0.62% | +30 mm | 59.6 mph | compare → |
| 285/45R19 | 29.10" | +0.22% | +30 mm | 60.1 mph | compare → |
| 335/30R21 | 28.91" | -0.42% | +80 mm | 59.7 mph | calculate → |
| 345/30R21 | 29.15" | +0.39% | +90 mm | 60.2 mph | calculate → |
| 225/45R21 | 28.97" | -0.22% | -30 mm | 59.9 mph | calculate → |
| 315/40R19 | 28.92" | -0.39% | +60 mm | 59.8 mph | calculate → |
| 155/80R19 | 28.76" | -0.94% | -100 mm | 59.4 mph | calculate → |
Try another size against 255/45R20
Questions
What size is 255/45R20 in inches?
255/45R20 is about 29.0" tall and 10.0" wide on a 20-inch rim — roughly a 29x10.00R20 in inch sizing.
What does 255/45R20 mean?
255 mm section width, sidewall 45% of the width (4.52"), radial construction, 20-inch rim.
What tire sizes are equivalent to 255/45R20?
On the same 20" rim, within 3% of the diameter: 29x15.00R20 (-0.12%), 29x18.00R20 (-0.12%), 285/40R20 (-0.20%), 325/35R20 (-0.27%), 235/50R20 (+0.75%), 295/40R20 (+0.88%).
How many revolutions per mile does a 255/45R20 tire make?
About 695 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.