245/70R18 Tire Size in Inches

31.5" tall, 9.6" wide, 6.8" sidewall

Diameter31.5"800 mm
Overall diameter31.5"800 mm
Section width9.6"245 mm
Sidewall height6.8"172 mm
Circumference99.0"2514 mm
Revolutions per mile640398 per km
Wheel diameter18"≈ 31.5x9.6R18 in inches

A 245/70R18 tire is 31.5 inches (800 mm) tall and 9.6 inches wide. The sidewall is 70% of the width, 6.8 inches, on a 18-inch wheel, and the tire turns about 640 times per mile.

In flotation terms that is about 31.5x9.6R18. People often call it a 32-inch tire.

The size most often compared with it is 265/65R18, which is 0.1" taller (+0.2%). At an indicated 60 mph you would be doing 60.1 mph on it.

245/70R18
265/65R18
Diameter difference+0.19%diameter 31.50" → 31.56"
CurrentNew
CurrentNewDifference

Speedometer

ShowsActual speed

Gear ratio to match

–enter your current axle ratio

Sizes near 245/70R18

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

SizeDiameterWidthSidewallvs 245/70R18
265/65R1831.6"10.4"6.8"+0.2%
235/75R1831.9"9.3"6.9"+1.2%
255/70R1832.1"10.0"7.0"+1.7%
245/65R1830.5"9.6"6.3"−3.1%
245/75R1832.5"9.6"7.2"+3.1%
265/70R1832.6"10.4"7.3"+3.5%
235/80R1832.8"9.3"7.4"+4.1%
255/75R1833.1"10.0"7.5"+4.9%
265/75R1833.6"10.4"7.8"+6.8%
255/80R1834.1"10.0"8.0"+8.1%

Same height on a different wheel

Sizes within 2% of 31.5" on 20" or 17" or 16" wheels.

SizeDiameterWidthSidewallvs 245/70R18
265/55R2031.5"10.4"5.7"−0.1%
245/75R1731.5"9.6"7.2"−0.1%
245/60R2031.6"9.6"5.8"+0.2%
245/80R1631.4"9.6"7.7"−0.2%
285/65R1731.6"11.2"7.3"+0.3%
305/60R1731.4"12.0"7.2"−0.3%

Speedometer with a different size

Actual speed when the speedometer is calibrated for 245/70R18.

Speedometer showson 265/65R18on 235/75R18on 255/70R18
30 mph30.1 mph30.4 mph30.5 mph
45 mph45.1 mph45.5 mph45.8 mph
60 mph60.1 mph60.7 mph61.0 mph
70 mph70.1 mph70.8 mph71.2 mph

245/70R18 FAQ

How tall is a 245/70R18 tire?

31.5 inches (800 mm). The sidewall is 6.8 inches.

How wide is a 245/70R18 tire?

9.6 inches (245 mm) section width, measured sidewall to sidewall.

What is 245/70R18 in flotation size?

About 31.5x9.6R18.

Can I use 265/65R18 instead of 245/70R18?

265/65R18 is +0.2% in diameter, within the common 3% guideline. It is 0.8" wider.