285/30R18 Tire Size in Inches

24.7" tall, 11.2" wide, 3.4" sidewall

Diameter24.7"628 mm
Overall diameter24.7"628 mm
Section width11.2"285 mm
Sidewall height3.4"86 mm
Circumference77.7"1974 mm
Revolutions per mile815507 per km
Wheel diameter18"≈ 24.7x11.2R18 in inches

A 285/30R18 tire is 24.7 inches (628 mm) tall and 11.2 inches wide. The sidewall is 30% of the width, 3.4 inches, on a 18-inch wheel, and the tire turns about 815 times per mile.

In flotation terms that is about 24.7x11.2R18. People often call it a 25-inch tire.

The size most often compared with it is 295/30R18, which is 0.2" taller (+1.0%). At an indicated 60 mph you would be doing 60.6 mph on it.

285/30R18
295/30R18
Diameter difference+0.96%diameter 24.73" → 24.97"
CurrentNew
CurrentNewDifference

Speedometer

ShowsActual speed

Gear ratio to match

–enter your current axle ratio

Sizes near 285/30R18

Same 18" wheel, within 20 mm of width and 10 points of aspect ratio.

SizeDiameterWidthSidewallvs 285/30R18
295/30R1825.0"11.6"3.5"+1.0%
275/30R1824.5"10.8"3.2"−1.0%
305/30R1825.2"12.0"3.6"+1.9%
265/35R1825.3"10.4"3.7"+2.3%
275/35R1825.6"10.8"3.8"+3.4%
285/35R1825.9"11.2"3.9"+4.5%
295/35R1826.1"11.6"4.1"+5.7%
265/40R1826.3"10.4"4.2"+6.5%
305/35R1826.4"12.0"4.2"+6.8%
275/40R1826.7"10.8"4.3"+7.8%

Same height on a different wheel

Sizes within 2% of 24.7" on 17" or 16" wheels.

SizeDiameterWidthSidewallvs 285/30R18
245/40R1724.7"9.6"3.9"−0.1%
225/50R1624.9"8.9"4.4"+0.5%
275/35R1724.6"10.8"3.8"−0.6%
215/50R1624.5"8.5"4.2"−1.1%
185/55R1725.0"7.3"4.0"+1.1%
255/40R1725.0"10.0"4.0"+1.2%

Speedometer with a different size

Actual speed when the speedometer is calibrated for 285/30R18.

Speedometer showson 295/30R18on 275/30R18on 305/30R18
30 mph30.3 mph29.7 mph30.6 mph
45 mph45.4 mph44.6 mph45.9 mph
60 mph60.6 mph59.4 mph61.1 mph
70 mph70.7 mph69.3 mph71.3 mph

285/30R18 FAQ

How tall is a 285/30R18 tire?

24.7 inches (628 mm). The sidewall is 3.4 inches.

How wide is a 285/30R18 tire?

11.2 inches (285 mm) section width, measured sidewall to sidewall.

What is 285/30R18 in flotation size?

About 24.7x11.2R18.

Can I use 295/30R18 instead of 285/30R18?

295/30R18 is +1.0% in diameter, within the common 3% guideline. It is 0.4" wider.