275/40R20 tire size in inches

A 275/40R20 tire measures

28.7" tall × 10.8" wide

4.33" sidewall on a 20" wheel. 704 revolutions per mile.

275/40R20 means a tire 275 mm wide, with sidewalls 40% as tall as the tire is wide (110 mm), radial construction (R), for a 20 inch wheel.

28.7"20" rim4.3"10.8" wide
275/40R20: 28.7 inches tall, 10.8 inches wide, on a 20 inch rim, drawn to scale

275/40R20 specs

Overall diameter (height)28.66 inches (728 mm)
Section width10.83 inches (275 mm)
Sidewall height4.33 inches (110 mm)
Wheel (rim) diameter20 inches
Circumference90.0 inches (2,287 mm)
Revolutions per mile704
Revolutions per kilometer437
Approximate rim width9.0" to 10.5"
In inches (flotation style)28.7x10.8R20
Aspect ratio40%

Calculated from the size. Real tires differ by brand, model and tread depth, typically by a few tenths of an inch.

Sizes that can replace 275/40R20 on a 20" wheel

These 20" sizes are within 3% of 275/40R20's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
245/45R2028.68"9.65"+0.1%60.0 mphCompare
315/35R2028.68"12.40"+0.1%60.0 mphCompare
215/50R2028.46"8.46"−0.7%59.6 mphCompare
225/50R2028.86"8.86"+0.7%60.4 mphCompare
305/35R2028.41"12.01"−0.9%59.5 mphCompare
355/30R2028.39"13.98"−1.0%59.4 mphCompare
325/35R2028.96"12.80"+1.0%60.6 mphCompare
265/40R2028.35"10.43"−1.1%59.3 mphCompare
285/40R2028.98"11.22"+1.1%60.7 mphCompare
235/45R2028.33"9.25"−1.2%59.3 mphCompare
255/45R2029.04"10.04"+1.3%60.8 mphCompare
345/30R2028.15"13.58"−1.8%58.9 mphCompare

Same height on other wheel sizes (plus and minus sizing)

SizeWheelDiameterDifference
245/50R1919"28.65"−0.1%Compare
325/30R2121"28.68"+0.1%Compare
205/60R1919"28.69"+0.1%Compare
225/60R1818"28.63"−0.1%Compare
215/75R1616"28.70"+0.1%Compare
295/50R1717"28.61"−0.2%Compare
245/55R1818"28.61"−0.2%Compare
265/70R1414"28.61"−0.2%Compare
305/40R1919"28.61"−0.2%Compare
245/40R2121"28.72"+0.2%Compare
205/85R1515"28.72"+0.2%Compare
335/25R2222"28.59"−0.2%Compare

One size up or down

Compare 275/40R20 with another size

With 285/40R20 tires, when your speedometer says 60 mph you are really going

60.7 mph

285/40R20 is +0.31 inches (+1.1%) in overall diameter. That is within the 3% most shops and makers allow.

275/40R20285/40R20Difference%
Overall diameter28.66"28.98"+0.31"+1.1%
Section width10.83"11.22"+0.39"+3.6%
Sidewall height4.33"4.49"+0.16"+3.6%
Circumference90.04"91.03"+0.99"+1.1%
Revolutions per mile703.7696.0−7.6−1.1%

Questions

How tall is a 275/40R20 tire?
A 275/40R20 tire is 28.7 inches tall (728 mm), calculated from the size. It is 10.8 inches wide with 4.3 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 275/40R20 mean?
275/40R20 means a tire 275 mm wide, with sidewalls 40% as tall as the tire is wide (110 mm), radial construction (R), for a 20 inch wheel.
How many revolutions per mile does a 275/40R20 tire make?
About 704 revolutions per mile, based on a circumference of 90.0 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 275/40R20 tire?
Roughly 9.0" to 10.5". Check the tire maker's approved rim range for the exact model before buying wheels.
Can I use 245/45R20 instead of 275/40R20?
245/45R20 is +0.02 inches (+0.1%) in overall diameter, so at an indicated 60 mph you would be doing 60.0 mph. Differences under 3% are usually fine, but check clearance, load index and your vehicle's placard.

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