235/40R20 tire size
235/40R20 is a metric size: 27.4" tall, 9.3" wide, on a 20" rim — about a 27.5x9.50R20. The sidewall is 3.7" and the tire turns 736 times per mile.
235/40R20 specs
| Overall diameter (height) | 27.40" · 696 mm |
|---|---|
| Section width | 9.25" · 235 mm |
| Sidewall height | 3.70" · 94 mm (40% of width) |
| Rim diameter | 20" |
| Circumference | 86.08" · 2.187 m |
| Revolutions per mile | 736 (457 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" | +4.67% | +10 mm | 62.8 mph | calculate → |
| 275/40R20 common | 28.66" | +4.60% | +40 mm | 62.8 mph | calculate → |
| 245/40R20 common | 27.72" | +1.15% | +10 mm | 60.7 mph | calculate → |
| 245/35R20 common | 26.75" | -2.37% | +10 mm | 58.6 mph | calculate → |
| 255/35R20 common | 27.03" | -1.36% | +20 mm | 59.2 mph | calculate → |
| 275/35R20 common | 27.58" | +0.65% | +40 mm | 60.4 mph | calculate → |
| 255/40R20 common | 28.03" | +2.30% | +20 mm | 61.4 mph | calculate → |
| 285/35R20 common | 27.85" | +1.65% | +50 mm | 61.0 mph | calculate → |
| 315/35R20 common | 28.68" | +4.67% | +80 mm | 62.8 mph | calculate → |
| 285/30R20 common | 26.73" | -2.44% | +50 mm | 58.5 mph | calculate → |
| 275/30R20 common | 26.50" | -3.30% | +40 mm | 58.0 mph | calculate → |
| 265/35R20 common | 27.30" | -0.36% | +30 mm | 59.8 mph | calculate → |
| 235/35R20 | 26.48" | -3.38% | 0 mm | 58.0 mph | calculate → |
| 295/30R20 | 26.97" | -1.58% | +60 mm | 59.1 mph | calculate → |
| 305/30R20 | 27.20" | -0.72% | +70 mm | 59.6 mph | calculate → |
| 295/35R20 | 28.13" | +2.66% | +60 mm | 61.6 mph | calculate → |
| 305/35R20 | 28.41" | +3.66% | +70 mm | 62.2 mph | calculate → |
| 265/30R20 | 26.26" | -4.17% | +30 mm | 57.5 mph | calculate → |
| 235/45R20 | 28.33" | +3.38% | 0 mm | 62.0 mph | calculate → |
| 225/35R20 | 26.20" | -4.38% | -10 mm | 57.4 mph | calculate → |
| 265/40R20 | 28.35" | +3.45% | +30 mm | 62.1 mph | calculate → |
| 335/25R20 | 26.59" | -2.95% | +100 mm | 58.2 mph | calculate → |
| 315/30R20 | 27.44" | +0.14% | +80 mm | 60.1 mph | calculate → |
| 335/30R20 | 27.91" | +1.87% | +100 mm | 61.1 mph | calculate → |
| 325/25R20 | 26.40" | -3.66% | +90 mm | 57.8 mph | calculate → |
| 325/30R20 | 27.68" | +1.01% | +90 mm | 60.6 mph | calculate → |
| 345/30R20 | 28.15" | +2.73% | +110 mm | 61.6 mph | calculate → |
| 215/45R20 | 27.62" | +0.79% | -20 mm | 60.5 mph | calculate → |
| 345/25R20 | 26.79" | -2.23% | +110 mm | 58.7 mph | calculate → |
| 195/50R20 | 27.68" | +1.01% | -40 mm | 60.6 mph | calculate → |
| 225/40R20 | 27.09" | -1.15% | -10 mm | 59.3 mph | calculate → |
| 145/65R20 | 27.42" | +0.07% | -90 mm | 60.0 mph | calculate → |
| 155/60R20 | 27.32" | -0.29% | -80 mm | 59.8 mph | calculate → |
| 175/55R20 | 27.58" | +0.65% | -60 mm | 60.4 mph | calculate → |
| 145/60R20 | 26.85" | -2.01% | -90 mm | 58.8 mph | calculate → |
| 165/60R20 | 27.80" | +1.44% | -70 mm | 60.9 mph | calculate → |
| 155/65R20 | 27.93" | +1.94% | -80 mm | 61.2 mph | calculate → |
| 225/45R20 | 27.97" | +2.08% | -10 mm | 61.2 mph | calculate → |
| 195/55R20 | 28.44" | +3.81% | -40 mm | 62.3 mph | calculate → |
| 315/25R20 | 26.20" | -4.38% | +80 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 | |
|---|---|---|---|---|---|
| 275/40R19 common | 27.66" | +0.95% | +40 mm | 60.6 mph | calculate → |
| 235/45R19 common | 27.33" | -0.27% | 0 mm | 59.8 mph | calculate → |
| 265/40R19 | 27.35" | -0.20% | +30 mm | 59.9 mph | calculate → |
| 295/35R19 | 27.13" | -0.99% | +60 mm | 59.4 mph | calculate → |
| 275/30R21 | 27.50" | +0.34% | +40 mm | 60.2 mph | calculate → |
| 345/30R19 | 27.15" | -0.92% | +110 mm | 59.4 mph | calculate → |
| 305/35R19 | 27.41" | +0.01% | +70 mm | 60.0 mph | calculate → |
| 155/70R19 | 27.54" | +0.52% | -80 mm | 60.3 mph | calculate → |
| 355/30R19 | 27.39" | -0.06% | +120 mm | 60.0 mph | calculate → |
| 265/30R21 | 27.26" | -0.52% | +30 mm | 59.7 mph | calculate → |
| 325/25R21 | 27.40" | -0.01% | +90 mm | 60.0 mph | calculate → |
| 215/50R19 | 27.46" | +0.23% | -20 mm | 60.1 mph | calculate → |
| 175/60R19 | 27.27" | -0.49% | -60 mm | 59.7 mph | calculate → |
Try another size against 235/40R20
Questions
What size is 235/40R20 in inches?
235/40R20 is about 27.4" tall and 9.3" wide on a 20-inch rim — roughly a 27.5x9.50R20 in inch sizing.
What does 235/40R20 mean?
235 mm section width, sidewall 40% of the width (3.70"), radial construction, 20-inch rim.
What tire sizes are equivalent to 235/40R20?
On the same 20" rim, within 3% of the diameter: 145/65R20 (+0.07%), 315/30R20 (+0.14%), 155/60R20 (-0.29%), 265/35R20 (-0.36%), 175/55R20 (+0.65%), 275/35R20 (+0.65%).
How many revolutions per mile does a 235/40R20 tire make?
About 736 revolutions per mile (circumference 86.1").
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.