285/45R18 tire size in inches

A 285/45R18 tire measures

28.1" tall × 11.2" wide

5.05" sidewall on a 18" wheel. 718 revolutions per mile.

285/45R18 means a tire 285 mm wide, with sidewalls 45% as tall as the tire is wide (128 mm), radial construction (R), for a 18 inch wheel.

28.1"18" rim5.0"11.2" wide
285/45R18: 28.1 inches tall, 11.2 inches wide, on a 18 inch rim, drawn to scale

285/45R18 specs

Overall diameter (height)28.10 inches (714 mm)
Section width11.22 inches (285 mm)
Sidewall height5.05 inches (128 mm)
Wheel (rim) diameter18 inches
Circumference88.3 inches (2,242 mm)
Revolutions per mile718
Revolutions per kilometer446
Approximate rim width9.5" to 11.0"
In inches (flotation style)28.1x11.2R18
Aspect ratio45%

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 285/45R18 on a 18" wheel

These 18" sizes are within 3% of 285/45R18's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
215/60R1828.16"8.46"+0.2%60.1 mphCompare
255/50R1828.04"10.04"−0.2%59.9 mphCompare
235/55R1828.18"9.25"+0.3%60.2 mphCompare
195/65R1827.98"7.68"−0.4%59.7 mphCompare
325/40R1828.24"12.80"+0.5%60.3 mphCompare
315/40R1827.92"12.40"−0.6%59.6 mphCompare
265/50R1828.43"10.43"+1.2%60.7 mphCompare
225/55R1827.74"8.86"−1.3%59.2 mphCompare
275/45R1827.74"10.83"−1.3%59.2 mphCompare
295/45R1828.45"11.61"+1.3%60.8 mphCompare
205/65R1828.49"8.07"+1.4%60.8 mphCompare
205/60R1827.69"8.07"−1.5%59.1 mphCompare

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

SizeWheelDiameterDifference
235/60R1717"28.10"0.0%Compare
205/75R1616"28.11"0.0%Compare
225/40R2121"28.09"0.0%Compare
295/35R2020"28.13"+0.1%Compare
225/85R1313"28.06"−0.1%Compare
255/70R1414"28.06"−0.2%Compare
195/85R1515"28.05"−0.2%Compare
255/65R1515"28.05"−0.2%Compare
255/60R1616"28.05"−0.2%Compare
345/30R2020"28.15"+0.2%Compare
255/55R1717"28.04"−0.2%Compare
255/45R1919"28.04"−0.2%Compare

One size up or down

Compare 285/45R18 with another size

With 295/45R18 tires, when your speedometer says 60 mph you are really going

60.8 mph

295/45R18 is +0.35 inches (+1.3%) in overall diameter. That is within the 3% most shops and makers allow.

285/45R18295/45R18Difference%
Overall diameter28.10"28.45"+0.35"+1.3%
Section width11.22"11.61"+0.39"+3.5%
Sidewall height5.05"5.23"+0.18"+3.5%
Circumference88.27"89.39"+1.11"+1.3%
Revolutions per mile717.8708.8−8.9−1.2%

Questions

How tall is a 285/45R18 tire?
A 285/45R18 tire is 28.1 inches tall (714 mm), calculated from the size. It is 11.2 inches wide with 5.0 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 285/45R18 mean?
285/45R18 means a tire 285 mm wide, with sidewalls 45% as tall as the tire is wide (128 mm), radial construction (R), for a 18 inch wheel.
How many revolutions per mile does a 285/45R18 tire make?
About 718 revolutions per mile, based on a circumference of 88.3 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 285/45R18 tire?
Roughly 9.5" to 11.0". Check the tire maker's approved rim range for the exact model before buying wheels.
Can I use 215/60R18 instead of 285/45R18?
215/60R18 is +0.06 inches (+0.2%) in overall diameter, so at an indicated 60 mph you would be doing 60.1 mph. Differences under 3% are usually fine, but check clearance, load index and your vehicle's placard.

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