275/65R18 tire size in inches

A 275/65R18 tire measures

32.1" tall × 10.8" wide

7.04" sidewall on a 18" wheel. 629 revolutions per mile.

275/65R18 means a tire 275 mm wide, with sidewalls 65% as tall as the tire is wide (179 mm), radial construction (R), for a 18 inch wheel.

32.1"18" rim7.0"10.8" wide
275/65R18: 32.1 inches tall, 10.8 inches wide, on a 18 inch rim, drawn to scale

275/65R18 specs

Overall diameter (height)32.07 inches (815 mm)
Section width10.83 inches (275 mm)
Sidewall height7.04 inches (179 mm)
Wheel (rim) diameter18 inches
Circumference100.8 inches (2,559 mm)
Revolutions per mile629
Revolutions per kilometer391
Approximate rim width7.5" to 9.0"
In inches (flotation style)32.1x10.8R18
Aspect ratio65%

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 275/65R18 on a 18" wheel

These 18" sizes are within 3% of 275/65R18's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
325/55R1832.07"12.80"0.0%60.0 mphCompare
255/70R1832.06"10.04"−0.1%60.0 mphCompare
295/60R1831.94"11.61"−0.4%59.7 mphCompare
235/75R1831.88"9.25"−0.6%59.6 mphCompare
305/60R1832.41"12.01"+1.0%60.6 mphCompare
245/75R1832.47"9.65"+1.2%60.7 mphCompare
315/55R1831.64"12.40"−1.4%59.2 mphCompare
335/55R1832.51"13.19"+1.4%60.8 mphCompare
265/65R1831.56"10.43"−1.6%59.0 mphCompare
285/65R1832.59"11.22"+1.6%61.0 mphCompare
265/70R1832.61"10.43"+1.7%61.0 mphCompare
245/70R1831.50"9.65"−1.8%58.9 mphCompare

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

SizeWheelDiameterDifference
255/85R1515"32.07"0.0%Compare
255/80R1616"32.06"0.0%Compare
255/75R1717"32.06"0.0%Compare
255/65R1919"32.05"−0.1%Compare
285/45R2222"32.10"+0.1%Compare
295/65R1717"32.10"+0.1%Compare
255/60R2020"32.05"−0.1%Compare
255/55R2121"32.04"−0.1%Compare
255/50R2222"32.04"−0.1%Compare
255/40R2424"32.03"−0.1%Compare
235/65R2020"32.03"−0.1%Compare
295/35R2424"32.13"+0.2%Compare

One size up or down

Compare 275/65R18 with another size

With 285/65R18 tires, when your speedometer says 60 mph you are really going

61.0 mph

285/65R18 is +0.51 inches (+1.6%) in overall diameter. That is within the 3% most shops and makers allow.

275/65R18285/65R18Difference%
Overall diameter32.07"32.59"+0.51"+1.6%
Section width10.83"11.22"+0.39"+3.6%
Sidewall height7.04"7.29"+0.26"+3.6%
Circumference100.77"102.37"+1.61"+1.6%
Revolutions per mile628.8618.9−9.9−1.6%

Questions

How tall is a 275/65R18 tire?
A 275/65R18 tire is 32.1 inches tall (815 mm), calculated from the size. It is 10.8 inches wide with 7.0 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 275/65R18 mean?
275/65R18 means a tire 275 mm wide, with sidewalls 65% as tall as the tire is wide (179 mm), radial construction (R), for a 18 inch wheel.
How many revolutions per mile does a 275/65R18 tire make?
About 629 revolutions per mile, based on a circumference of 100.8 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 275/65R18 tire?
Roughly 7.5" to 9.0". Check the tire maker's approved rim range for the exact model before buying wheels.
Can I use 325/55R18 instead of 275/65R18?
325/55R18 is 0.00 inches (0.0%) 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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