285/40R20 tire size
285/40R20 is a metric size: 29.0" tall, 11.2" wide, on a 20" rim — about a 29x11.00R20. The sidewall is 4.5" and the tire turns 696 times per mile.
285/40R20 specs
| Overall diameter (height) | 28.98" · 736 mm |
|---|---|
| Section width | 11.22" · 285 mm |
| Sidewall height | 4.49" · 114 mm (40% of width) |
| Rim diameter | 20" |
| Circumference | 91.03" · 2.312 m |
| Revolutions per mile | 696 (432 per km) |
| Inch (flotation) equivalent | 29x11.00R20 |
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" | -1.02% | -40 mm | 59.4 mph | compare → |
| 255/45R20 common | 29.04" | +0.20% | -30 mm | 60.1 mph | compare → |
| 275/40R20 common | 28.66" | -1.09% | -10 mm | 59.3 mph | compare → |
| 255/50R20 common | 30.04" | +3.67% | -30 mm | 62.2 mph | compare → |
| 245/40R20 common | 27.72" | -4.35% | -40 mm | 57.4 mph | compare → |
| 245/50R20 common | 29.65" | +2.31% | -40 mm | 61.4 mph | compare → |
| 275/45R20 common | 29.74" | +2.65% | -10 mm | 61.6 mph | compare → |
| 235/55R20 common | 30.18" | +4.14% | -50 mm | 62.5 mph | compare → |
| 255/40R20 common | 28.03" | -3.26% | -30 mm | 58.0 mph | compare → |
| 275/35R20 common | 27.58" | -4.82% | -10 mm | 57.1 mph | compare → |
| 265/45R20 common | 29.39" | +1.43% | -20 mm | 60.9 mph | compare → |
| 285/35R20 common | 27.85" | -3.87% | 0 mm | 57.7 mph | compare → |
| 315/35R20 common | 28.68" | -1.02% | +30 mm | 59.4 mph | compare → |
| 295/40R20 | 29.29" | +1.09% | +10 mm | 60.7 mph | compare → |
| 295/35R20 | 28.13" | -2.92% | +10 mm | 58.2 mph | compare → |
| 305/35R20 | 28.41" | -1.97% | +20 mm | 58.8 mph | compare → |
| 235/50R20 | 29.25" | +0.95% | -50 mm | 60.6 mph | compare → |
| 235/45R20 | 28.33" | -2.24% | -50 mm | 58.7 mph | compare → |
| 285/45R20 | 30.10" | +3.87% | 0 mm | 62.3 mph | compare → |
| 265/40R20 | 28.35" | -2.17% | -20 mm | 58.7 mph | compare → |
| 305/40R20 | 29.61" | +2.17% | +20 mm | 61.3 mph | compare → |
| 335/30R20 | 27.91" | -3.67% | +50 mm | 57.8 mph | calculate → |
| 325/30R20 | 27.68" | -4.48% | +40 mm | 57.3 mph | calculate → |
| 345/30R20 | 28.15" | -2.85% | +60 mm | 58.3 mph | calculate → |
| 215/45R20 | 27.62" | -4.69% | -70 mm | 57.2 mph | calculate → |
| 325/35R20 | 28.96" | -0.07% | +40 mm | 60.0 mph | calculate → |
| 195/50R20 | 27.68" | -4.48% | -90 mm | 57.3 mph | calculate → |
| 29x15.00R20 | 29.00" | +0.08% | +96 mm | 60.0 mph | calculate → |
| 29x18.00R20 | 29.00" | +0.08% | +172 mm | 60.0 mph | calculate → |
| 175/55R20 | 27.58" | -4.82% | -110 mm | 57.1 mph | calculate → |
| 195/55R20 | 28.44" | -1.83% | -90 mm | 58.9 mph | calculate → |
| 175/70R20 | 29.65" | +2.31% | -110 mm | 61.4 mph | calculate → |
| 225/45R20 | 27.97" | -3.46% | -60 mm | 57.9 mph | calculate → |
| 155/65R20 | 27.93" | -3.60% | -130 mm | 57.8 mph | calculate → |
| 165/60R20 | 27.80" | -4.08% | -120 mm | 57.6 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" | +0.69% | -50 mm | 60.4 mph | compare → |
| 255/50R19 common | 29.04" | +0.22% | -30 mm | 60.1 mph | compare → |
| 225/55R19 common | 28.74" | -0.80% | -60 mm | 59.5 mph | compare → |
| 295/35R21 | 29.13" | +0.53% | +10 mm | 60.3 mph | compare → |
| 255/40R21 | 29.03" | +0.19% | -30 mm | 60.1 mph | compare → |
| 285/35R21 | 28.85" | -0.42% | 0 mm | 59.7 mph | compare → |
| 275/45R19 | 28.74" | -0.80% | -10 mm | 59.5 mph | compare → |
| 245/40R21 | 28.72" | -0.90% | -40 mm | 59.5 mph | compare → |
| 285/45R19 | 29.10" | +0.42% | 0 mm | 60.3 mph | compare → |
| 335/30R21 | 28.91" | -0.22% | +50 mm | 59.9 mph | calculate → |
| 345/30R21 | 29.15" | +0.60% | +60 mm | 60.4 mph | calculate → |
| 225/45R21 | 28.97" | -0.01% | -60 mm | 60.0 mph | calculate → |
| 315/40R19 | 28.92" | -0.19% | +30 mm | 59.9 mph | calculate → |
| 155/80R19 | 28.76" | -0.73% | -130 mm | 59.6 mph | calculate → |
Try another size against 285/40R20
Questions
What size is 285/40R20 in inches?
285/40R20 is about 29.0" tall and 11.2" wide on a 20-inch rim — roughly a 29x11.00R20 in inch sizing.
What does 285/40R20 mean?
285 mm section width, sidewall 40% of the width (4.49"), radial construction, 20-inch rim.
What tire sizes are equivalent to 285/40R20?
On the same 20" rim, within 3% of the diameter: 325/35R20 (-0.07%), 29x15.00R20 (+0.08%), 29x18.00R20 (+0.08%), 255/45R20 (+0.20%), 235/50R20 (+0.95%), 245/45R20 (-1.02%).
How many revolutions per mile does a 285/40R20 tire make?
About 696 revolutions per mile (circumference 91.0").
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.