195/75R18 tire size in inches

A 195/75R18 tire measures

29.5" tall × 7.7" wide

5.76" sidewall on a 18" wheel. 683 revolutions per mile.

195/75R18 means a tire 195 mm wide, with sidewalls 75% as tall as the tire is wide (146 mm), radial construction (R), for a 18 inch wheel.

29.5"18" rim5.8"7.7" wide
195/75R18: 29.5 inches tall, 7.7 inches wide, on a 18 inch rim, drawn to scale

195/75R18 specs

Overall diameter (height)29.52 inches (750 mm)
Section width7.68 inches (195 mm)
Sidewall height5.76 inches (146 mm)
Wheel (rim) diameter18 inches
Circumference92.7 inches (2,355 mm)
Revolutions per mile683
Revolutions per kilometer425
Approximate rim width5.0" to 6.5"
In inches (flotation style)29.5x7.7R18
Aspect ratio75%

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 195/75R18 on a 18" wheel

These 18" sizes are within 3% of 195/75R18's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
225/65R1829.52"8.86"0.0%60.0 mphCompare
325/45R1829.52"12.80"0.0%60.0 mphCompare
265/55R1829.48"10.43"−0.1%59.9 mphCompare
245/60R1829.57"9.65"+0.2%60.1 mphCompare
295/50R1829.61"11.61"+0.3%60.2 mphCompare
205/70R1829.30"8.07"−0.7%59.6 mphCompare
285/50R1829.22"11.22"−1.0%59.4 mphCompare
215/70R1829.85"8.46"+1.1%60.7 mphCompare
315/45R1829.16"12.40"−1.2%59.3 mphCompare
335/45R1829.87"13.19"+1.2%60.7 mphCompare
275/55R1829.91"10.83"+1.3%60.8 mphCompare
235/60R1829.10"9.25"−1.4%59.2 mphCompare

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

SizeWheelDiameterDifference
265/60R1717"29.52"0.0%Compare
345/35R2020"29.51"0.0%Compare
245/70R1616"29.50"0.0%Compare
205/65R1919"29.49"−0.1%Compare
245/65R1717"29.54"+0.1%Compare
215/80R1616"29.54"+0.1%Compare
335/40R1919"29.55"+0.1%Compare
245/75R1515"29.47"−0.2%Compare
265/65R1616"29.56"+0.2%Compare
285/60R1616"29.46"−0.2%Compare
275/35R2222"29.58"+0.2%Compare
295/45R1919"29.45"−0.2%Compare

One size up or down

Compare 195/75R18 with another size

With 205/75R18 tires, when your speedometer says 60 mph you are really going

61.2 mph

205/75R18 is +0.59 inches (+2.0%) in overall diameter. That is within the 3% most shops and makers allow.

195/75R18205/75R18Difference%
Overall diameter29.52"30.11"+0.59"+2.0%
Section width7.68"8.07"+0.39"+5.1%
Sidewall height5.76"6.05"+0.30"+5.1%
Circumference92.73"94.58"+1.86"+2.0%
Revolutions per mile683.3669.9−13.4−2.0%

Questions

How tall is a 195/75R18 tire?
A 195/75R18 tire is 29.5 inches tall (750 mm), calculated from the size. It is 7.7 inches wide with 5.8 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 195/75R18 mean?
195/75R18 means a tire 195 mm wide, with sidewalls 75% as tall as the tire is wide (146 mm), radial construction (R), for a 18 inch wheel.
How many revolutions per mile does a 195/75R18 tire make?
About 683 revolutions per mile, based on a circumference of 92.7 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 195/75R18 tire?
Roughly 5.0" to 6.5". Check the tire maker's approved rim range for the exact model before buying wheels.
Can I use 225/65R18 instead of 195/75R18?
225/65R18 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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