285/75R18 tire size in inches

A 285/75R18 tire measures

34.8" tall × 11.2" wide

8.42" sidewall on a 18" wheel. 579 revolutions per mile.

285/75R18 means a tire 285 mm wide, with sidewalls 75% as tall as the tire is wide (214 mm), radial construction (R), for a 18 inch wheel.

34.8"18" rim8.4"11.2" wide
285/75R18: 34.8 inches tall, 11.2 inches wide, on a 18 inch rim, drawn to scale

285/75R18 specs

Overall diameter (height)34.83 inches (885 mm)
Section width11.22 inches (285 mm)
Sidewall height8.42 inches (214 mm)
Wheel (rim) diameter18 inches
Circumference109.4 inches (2,779 mm)
Revolutions per mile579
Revolutions per kilometer360
Approximate rim width7.5" to 9.0"
In inches (flotation style)34.8x11.2R18
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 285/75R18 on a 18" wheel

These 18" sizes are within 3% of 285/75R18's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
305/70R1834.81"12.01"−0.1%60.0 mphCompare
35x12.50R1835.00"12.50"+0.5%60.3 mphCompare
325/65R1834.63"12.80"−0.6%59.7 mphCompare
335/65R1835.15"13.19"+0.9%60.5 mphCompare
315/70R1835.36"12.40"+1.5%60.9 mphCompare
295/70R1834.26"11.61"−1.6%59.0 mphCompare
275/75R1834.24"10.83"−1.7%59.0 mphCompare
295/75R1835.42"11.61"+1.7%61.0 mphCompare
315/65R1834.12"12.40"−2.0%58.8 mphCompare
335/60R1833.83"13.19"−2.9%58.3 mphCompare

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

SizeWheelDiameterDifference
335/60R1919"34.83"0.0%Compare
325/50R2222"34.80"−0.1%Compare
345/40R2424"34.87"+0.1%Compare
315/60R2020"34.88"+0.1%Compare
295/55R2222"34.78"−0.2%Compare
345/55R2020"34.94"+0.3%Compare
355/50R2121"34.98"+0.4%Compare
35x12.50R1515"35.00"+0.5%Compare
35x12.50R1717"35.00"+0.5%Compare
35x12.50R2020"35.00"+0.5%Compare
35x12.50R2222"35.00"+0.5%Compare
35x12.50R2424"35.00"+0.5%Compare

One size up or down

Compare 285/75R18 with another size

With 295/75R18 tires, when your speedometer says 60 mph you are really going

61.0 mph

295/75R18 is +0.59 inches (+1.7%) in overall diameter. That is within the 3% most shops and makers allow.

285/75R18295/75R18Difference%
Overall diameter34.83"35.42"+0.59"+1.7%
Section width11.22"11.61"+0.39"+3.5%
Sidewall height8.42"8.71"+0.30"+3.5%
Circumference109.42"111.28"+1.86"+1.7%
Revolutions per mile579.0569.4−9.7−1.7%

Questions

How tall is a 285/75R18 tire?
A 285/75R18 tire is 34.8 inches tall (885 mm), calculated from the size. It is 11.2 inches wide with 8.4 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 285/75R18 mean?
285/75R18 means a tire 285 mm wide, with sidewalls 75% as tall as the tire is wide (214 mm), radial construction (R), for a 18 inch wheel.
How many revolutions per mile does a 285/75R18 tire make?
About 579 revolutions per mile, based on a circumference of 109.4 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 285/75R18 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 305/70R18 instead of 285/75R18?
305/70R18 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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