195/55R18 tire size in inches

A 195/55R18 tire measures

26.4" tall × 7.7" wide

4.22" sidewall on a 18" wheel. 763 revolutions per mile.

195/55R18 means a tire 195 mm wide, with sidewalls 55% as tall as the tire is wide (107 mm), radial construction (R), for a 18 inch wheel.

26.4"18" rim4.2"7.7" wide
195/55R18: 26.4 inches tall, 7.7 inches wide, on a 18 inch rim, drawn to scale

195/55R18 specs

Overall diameter (height)26.44 inches (672 mm)
Section width7.68 inches (195 mm)
Sidewall height4.22 inches (107 mm)
Wheel (rim) diameter18 inches
Circumference83.1 inches (2,110 mm)
Revolutions per mile763
Revolutions per kilometer474
Approximate rim width5.5" to 7.0"
In inches (flotation style)26.4x7.7R18
Aspect ratio55%

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 195/55R18 on a 18" wheel

These 18" sizes are within 3% of 195/55R18's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
215/50R1826.46"8.46"+0.1%60.0 mphCompare
305/35R1826.41"12.01"−0.1%59.9 mphCompare
265/40R1826.35"10.43"−0.4%59.8 mphCompare
235/45R1826.33"9.25"−0.4%59.7 mphCompare
275/40R1826.66"10.83"+0.8%60.5 mphCompare
245/45R1826.68"9.65"+0.9%60.5 mphCompare
315/35R1826.68"12.40"+0.9%60.5 mphCompare
295/35R1826.13"11.61"−1.2%59.3 mphCompare
205/50R1826.07"8.07"−1.4%59.2 mphCompare
255/40R1826.03"10.04"−1.6%59.1 mphCompare
225/50R1826.86"8.86"+1.6%60.9 mphCompare
205/55R1826.88"8.07"+1.6%61.0 mphCompare

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

SizeWheelDiameterDifference
315/30R1919"26.44"0.0%Compare
295/45R1616"26.45"0.0%Compare
265/50R1616"26.43"0.0%Compare
185/65R1717"26.47"+0.1%Compare
235/35R2020"26.48"+0.1%Compare
265/55R1515"26.48"+0.1%Compare
275/25R2121"26.41"−0.1%Compare
225/70R1414"26.40"−0.2%Compare
235/40R1919"26.40"−0.2%Compare
325/25R2020"26.40"−0.2%Compare
205/65R1616"26.49"+0.2%Compare
275/30R2020"26.50"+0.2%Compare

One size up or down

Compare 195/55R18 with another size

With 205/55R18 tires, when your speedometer says 60 mph you are really going

61.0 mph

205/55R18 is +0.43 inches (+1.6%) in overall diameter. That is within the 3% most shops and makers allow.

195/55R18205/55R18Difference%
Overall diameter26.44"26.88"+0.43"+1.6%
Section width7.68"8.07"+0.39"+5.1%
Sidewall height4.22"4.44"+0.22"+5.1%
Circumference83.08"84.44"+1.36"+1.6%
Revolutions per mile762.6750.4−12.3−1.6%

Questions

How tall is a 195/55R18 tire?
A 195/55R18 tire is 26.4 inches tall (672 mm), calculated from the size. It is 7.7 inches wide with 4.2 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 195/55R18 mean?
195/55R18 means a tire 195 mm wide, with sidewalls 55% as tall as the tire is wide (107 mm), radial construction (R), for a 18 inch wheel.
How many revolutions per mile does a 195/55R18 tire make?
About 763 revolutions per mile, based on a circumference of 83.1 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 195/55R18 tire?
Roughly 5.5" to 7.0". Check the tire maker's approved rim range for the exact model before buying wheels.
Can I use 215/50R18 instead of 195/55R18?
215/50R18 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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