275/30R20 tire size in inches

A 275/30R20 tire measures

26.5" tall × 10.8" wide

3.25" sidewall on a 20" wheel. 761 revolutions per mile.

275/30R20 means a tire 275 mm wide, with sidewalls 30% as tall as the tire is wide (83 mm), radial construction (R), for a 20 inch wheel.

26.5"20" rim3.2"10.8" wide
275/30R20: 26.5 inches tall, 10.8 inches wide, on a 20 inch rim, drawn to scale

275/30R20 specs

Overall diameter (height)26.50 inches (673 mm)
Section width10.83 inches (275 mm)
Sidewall height3.25 inches (83 mm)
Wheel (rim) diameter20 inches
Circumference83.2 inches (2,114 mm)
Revolutions per mile761
Revolutions per kilometer473
Approximate rim width9.0" to 10.5"
In inches (flotation style)26.5x10.8R20
Aspect ratio30%

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 275/30R20 on a 20" wheel

These 20" sizes are within 3% of 275/30R20's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
235/35R2026.48"9.25"−0.1%60.0 mphCompare
325/25R2026.40"12.80"−0.4%59.8 mphCompare
335/25R2026.59"13.19"+0.4%60.2 mphCompare
265/30R2026.26"10.43"−0.9%59.5 mphCompare
285/30R2026.73"11.22"+0.9%60.5 mphCompare
245/35R2026.75"9.65"+1.0%60.6 mphCompare
215/40R2026.77"8.46"+1.0%60.6 mphCompare
225/35R2026.20"8.86"−1.1%59.3 mphCompare
315/25R2026.20"12.40"−1.1%59.3 mphCompare
345/25R2026.79"13.58"+1.1%60.7 mphCompare
255/30R2026.02"10.04"−1.8%58.9 mphCompare
295/30R2026.97"11.61"+1.8%61.1 mphCompare

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

SizeWheelDiameterDifference
205/65R1616"26.49"0.0%Compare
245/70R1313"26.50"0.0%Compare
195/75R1515"26.52"+0.1%Compare
225/65R1515"26.52"+0.1%Compare
265/55R1515"26.48"−0.1%Compare
265/60R1414"26.52"+0.1%Compare
185/65R1717"26.47"−0.1%Compare
215/50R1818"26.46"−0.1%Compare
245/65R1414"26.54"+0.2%Compare
295/45R1616"26.45"−0.2%Compare
215/80R1313"26.54"+0.2%Compare
195/55R1818"26.44"−0.2%Compare

One size up or down

Compare 275/30R20 with another size

With 285/30R20 tires, when your speedometer says 60 mph you are really going

60.5 mph

285/30R20 is +0.24 inches (+0.9%) in overall diameter. That is within the 3% most shops and makers allow.

275/30R20285/30R20Difference%
Overall diameter26.50"26.73"+0.24"+0.9%
Section width10.83"11.22"+0.39"+3.6%
Sidewall height3.25"3.37"+0.12"+3.6%
Circumference83.24"83.98"+0.74"+0.9%
Revolutions per mile761.2754.4−6.7−0.9%

Questions

How tall is a 275/30R20 tire?
A 275/30R20 tire is 26.5 inches tall (673 mm), calculated from the size. It is 10.8 inches wide with 3.2 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 275/30R20 mean?
275/30R20 means a tire 275 mm wide, with sidewalls 30% as tall as the tire is wide (83 mm), radial construction (R), for a 20 inch wheel.
How many revolutions per mile does a 275/30R20 tire make?
About 761 revolutions per mile, based on a circumference of 83.2 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 275/30R20 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 235/35R20 instead of 275/30R20?
235/35R20 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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