245/40R20 tire size
245/40R20 is a metric size: 27.7" tall, 9.6" wide, on a 20" rim — about a 27.5x9.50R20. The sidewall is 3.9" and the tire turns 728 times per mile.
245/40R20 specs
| Overall diameter (height) | 27.72" · 704 mm |
|---|---|
| Section width | 9.65" · 245 mm |
| Sidewall height | 3.86" · 98 mm (40% of width) |
| Rim diameter | 20" |
| Circumference | 87.07" · 2.212 m |
| Revolutions per mile | 728 (452 per km) |
| Inch (flotation) equivalent | 27.5x9.50R20 |
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" | +3.48% | 0 mm | 62.1 mph | compare → |
| 255/45R20 common | 29.04" | +4.76% | +10 mm | 62.9 mph | compare → |
| 275/40R20 common | 28.66" | +3.41% | +30 mm | 62.0 mph | compare → |
| 245/35R20 common | 26.75" | -3.48% | 0 mm | 57.9 mph | compare → |
| 255/35R20 common | 27.03" | -2.49% | +10 mm | 58.5 mph | compare → |
| 275/35R20 common | 27.58" | -0.50% | +30 mm | 59.7 mph | compare → |
| 255/40R20 common | 28.03" | +1.14% | +10 mm | 60.7 mph | compare → |
| 285/35R20 common | 27.85" | +0.50% | +40 mm | 60.3 mph | compare → |
| 315/35R20 common | 28.68" | +3.48% | +70 mm | 62.1 mph | compare → |
| 285/30R20 common | 26.73" | -3.55% | +40 mm | 57.9 mph | compare → |
| 275/30R20 common | 26.50" | -4.40% | +30 mm | 57.4 mph | compare → |
| 265/35R20 common | 27.30" | -1.49% | +20 mm | 59.1 mph | compare → |
| 235/35R20 | 26.48" | -4.47% | -10 mm | 57.3 mph | compare → |
| 295/30R20 | 26.97" | -2.70% | +50 mm | 58.4 mph | compare → |
| 305/30R20 | 27.20" | -1.85% | +60 mm | 58.9 mph | compare → |
| 295/35R20 | 28.13" | +1.49% | +50 mm | 60.9 mph | compare → |
| 305/35R20 | 28.41" | +2.49% | +60 mm | 61.5 mph | compare → |
| 285/40R20 | 28.98" | +4.55% | +40 mm | 62.7 mph | compare → |
| 235/45R20 | 28.33" | +2.20% | -10 mm | 61.3 mph | compare → |
| 265/40R20 | 28.35" | +2.27% | +20 mm | 61.4 mph | compare → |
| 335/25R20 | 26.59" | -4.05% | +90 mm | 57.6 mph | compare → |
| 315/30R20 | 27.44" | -0.99% | +70 mm | 59.4 mph | compare → |
| 235/40R20 | 27.40" | -1.14% | -10 mm | 59.3 mph | calculate → |
| 335/30R20 | 27.91" | +0.71% | +90 mm | 60.4 mph | calculate → |
| 325/25R20 | 26.40" | -4.76% | +80 mm | 57.1 mph | calculate → |
| 325/30R20 | 27.68" | -0.14% | +80 mm | 59.9 mph | calculate → |
| 345/30R20 | 28.15" | +1.56% | +100 mm | 60.9 mph | calculate → |
| 215/45R20 | 27.62" | -0.36% | -30 mm | 59.8 mph | calculate → |
| 345/25R20 | 26.79" | -3.34% | +100 mm | 58.0 mph | calculate → |
| 195/50R20 | 27.68" | -0.14% | -50 mm | 59.9 mph | calculate → |
| 225/40R20 | 27.09" | -2.27% | -20 mm | 58.6 mph | calculate → |
| 325/35R20 | 28.96" | +4.47% | +80 mm | 62.7 mph | calculate → |
| 175/55R20 | 27.58" | -0.50% | -70 mm | 59.7 mph | calculate → |
| 145/65R20 | 27.42" | -1.07% | -100 mm | 59.4 mph | calculate → |
| 155/60R20 | 27.32" | -1.42% | -90 mm | 59.1 mph | calculate → |
| 145/60R20 | 26.85" | -3.13% | -100 mm | 58.1 mph | calculate → |
| 29x15.00R20 | 29.00" | +4.63% | +136 mm | 62.8 mph | calculate → |
| 29x18.00R20 | 29.00" | +4.63% | +212 mm | 62.8 mph | calculate → |
| 165/60R20 | 27.80" | +0.28% | -80 mm | 60.2 mph | calculate → |
| 155/65R20 | 27.93" | +0.78% | -90 mm | 60.5 mph | calculate → |
| 225/45R20 | 27.97" | +0.92% | -20 mm | 60.6 mph | calculate → |
| 195/55R20 | 28.44" | +2.63% | -50 mm | 61.6 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 | |
|---|---|---|---|---|---|
| 245/45R19 common | 27.68" | -0.13% | 0 mm | 59.9 mph | compare → |
| 275/40R19 common | 27.66" | -0.20% | +30 mm | 59.9 mph | compare → |
| 245/35R21 | 27.75" | +0.13% | 0 mm | 60.1 mph | compare → |
| 285/40R19 | 27.98" | +0.94% | +40 mm | 60.6 mph | compare → |
| 295/30R21 | 27.97" | +0.91% | +50 mm | 60.5 mph | compare → |
| 285/30R21 | 27.73" | +0.06% | +40 mm | 60.0 mph | compare → |
| 275/30R21 | 27.50" | -0.80% | +30 mm | 59.5 mph | compare → |
| 355/25R21 | 27.99" | +0.98% | +110 mm | 60.6 mph | calculate → |
| 155/70R19 | 27.54" | -0.62% | -90 mm | 59.6 mph | calculate → |
| 345/25R21 | 27.79" | +0.27% | +100 mm | 60.2 mph | calculate → |
| 215/50R19 | 27.46" | -0.91% | -30 mm | 59.5 mph | calculate → |
| 315/35R19 | 27.68" | -0.13% | +70 mm | 59.9 mph | calculate → |
| 225/50R19 | 27.86" | +0.51% | -20 mm | 60.3 mph | calculate → |
Try another size against 245/40R20
Questions
What size is 245/40R20 in inches?
245/40R20 is about 27.7" tall and 9.6" wide on a 20-inch rim — roughly a 27.5x9.50R20 in inch sizing.
What does 245/40R20 mean?
245 mm section width, sidewall 40% of the width (3.86"), radial construction, 20-inch rim.
What tire sizes are equivalent to 245/40R20?
On the same 20" rim, within 3% of the diameter: 195/50R20 (-0.14%), 325/30R20 (-0.14%), 165/60R20 (+0.28%), 215/45R20 (-0.36%), 175/55R20 (-0.50%), 275/35R20 (-0.50%).
How many revolutions per mile does a 245/40R20 tire make?
About 728 revolutions per mile (circumference 87.1").
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.