275/50R21 tire size in inches

A 275/50R21 tire measures

31.8" tall × 10.8" wide

5.41" sidewall on a 21" wheel. 634 revolutions per mile.

275/50R21 means a tire 275 mm wide, with sidewalls 50% as tall as the tire is wide (138 mm), radial construction (R), for a 21 inch wheel.

31.8"21" rim5.4"10.8" wide
275/50R21: 31.8 inches tall, 10.8 inches wide, on a 21 inch rim, drawn to scale

275/50R21 specs

Overall diameter (height)31.83 inches (808 mm)
Section width10.83 inches (275 mm)
Sidewall height5.41 inches (138 mm)
Wheel (rim) diameter21 inches
Circumference100.0 inches (2,540 mm)
Revolutions per mile634
Revolutions per kilometer394
Approximate rim width8.0" to 9.5"
In inches (flotation style)31.8x10.8R21
Aspect ratio50%

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 275/50R21 on a 21" wheel

These 21" sizes are within 3% of 275/50R21's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
305/45R2131.81"12.01"−0.1%60.0 mphCompare
345/40R2131.87"13.58"+0.1%60.1 mphCompare
245/55R2131.61"9.65"−0.7%59.6 mphCompare
255/55R2132.04"10.04"+0.7%60.4 mphCompare
335/40R2131.55"13.19"−0.9%59.5 mphCompare
315/45R2132.16"12.40"+1.1%60.6 mphCompare
355/40R2132.18"13.98"+1.1%60.7 mphCompare
295/45R2131.45"11.61"−1.2%59.3 mphCompare
265/50R2131.43"10.43"−1.2%59.3 mphCompare
285/50R2132.22"11.22"+1.2%60.7 mphCompare
325/40R2131.24"12.80"−1.9%58.9 mphCompare
235/55R2131.18"9.25"−2.0%58.8 mphCompare

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

SizeWheelDiameterDifference
285/75R1515"31.83"0.0%Compare
285/35R2424"31.85"+0.1%Compare
325/50R1919"31.80"−0.1%Compare
335/45R2020"31.87"+0.1%Compare
355/35R2222"31.78"−0.1%Compare
235/75R1818"31.88"+0.2%Compare
295/55R1919"31.78"−0.2%Compare
315/60R1717"31.88"+0.2%Compare
275/55R2020"31.91"+0.3%Compare
275/45R2222"31.74"−0.3%Compare
335/30R2424"31.91"+0.3%Compare
265/85R1414"31.74"−0.3%Compare

One size up or down

Compare 275/50R21 with another size

With 285/50R21 tires, when your speedometer says 60 mph you are really going

60.7 mph

285/50R21 is +0.39 inches (+1.2%) in overall diameter. That is within the 3% most shops and makers allow.

275/50R21285/50R21Difference%
Overall diameter31.83"32.22"+0.39"+1.2%
Section width10.83"11.22"+0.39"+3.6%
Sidewall height5.41"5.61"+0.20"+3.6%
Circumference99.99"101.22"+1.24"+1.2%
Revolutions per mile633.7625.9−7.7−1.2%

Questions

How tall is a 275/50R21 tire?
A 275/50R21 tire is 31.8 inches tall (808 mm), calculated from the size. It is 10.8 inches wide with 5.4 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 275/50R21 mean?
275/50R21 means a tire 275 mm wide, with sidewalls 50% as tall as the tire is wide (138 mm), radial construction (R), for a 21 inch wheel.
How many revolutions per mile does a 275/50R21 tire make?
About 634 revolutions per mile, based on a circumference of 100.0 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 275/50R21 tire?
Roughly 8.0" to 9.5". Check the tire maker's approved rim range for the exact model before buying wheels.
Can I use 305/45R21 instead of 275/50R21?
305/45R21 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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