305/70R18 Tire Size in Inches and Millimeters

305/70R18 tires have a diameter of 34.8" (885 mm), a tread width of 12" (305 mm), and a wheel diameter of 18" (457.2 mm).The sidewall of the tire is 8.4" (214 mm), and the tire's circumference is 109.3" (2778.9 mm). This means a 305/70R18 tire will make make 580 revolutions per mile, or 360 revolutions per kilometer.

305/70R18 Tire Front
12"
34.8"
305/70R18 Tire Side
Tire Circumference
109.3"
18"
8.4"
580 Revs/Mile
SpecInchesMetric
Diameter34.8"885 mm
Width12"305 mm
Wheel18"457.2 mm
Sidewall8.4"214 mm
Circum109.3"2778.9 mm
Revolutions580 per mile360 per km

What Does 305/70R18 Mean?

The tire size 305/70R18 is a common size used on many trucks, SUVs, and other larger vehicles.

Here is what each part of the size designation represents:

  • 305: This number represents the width of the tire in millimeters. In this case, the tire is 305 millimeters wide.
  • 70: This number represents the aspect ratio of the tire, which is the height of the tire's sidewall as a percentage of its width. In this case, the sidewall height is 70% of the tire's width.
  • R: This letter indicates the tire's construction type. “R” stands for radial construction, which is the most common type of tire construction today.
  • 18: This number represents the diameter of the wheel that the tire is designed to fit on, in inches. In this case, the tire is designed to fit on a 18-inch wheel.

305/70R18 tire size meaning

How To Convert 305/70R18 Into Inches

The 305/70R18 conversion is fairly simple. The first number in the tire size, 305, represents the width of the tire in millimeters. To convert this to inches, we divide 305 by 25.4 (since there are 25.4 millimeters in an inch). This gives us approximately 12 inches.

The second number in the tire size, 70, represents the aspect ratio or the height of the tire as a percentage of its width. To calculate the height in inches, we multiply 12 by 0.70, which gives us approximately 8.4 inches.

Finally, the last number in the tire size, 18, represents the diameter of the wheel rim in inches. Therefore, the tire size 305/70R18 can be expressed in inches as roughly 12 inches wide, 8.4 inches tall, and designed to fit a 18-inch wheel rim.

Frequently Asked Questions About 305/70R18 Tires

How tall is a 305/70R18 tire?

A 305/70R18 tire has an approximate height, also known as the overall diameter, of 34.8 inches (885 mm). This height can vary slightly depending on the brand and model of the tire, as well as the amount of air pressure in the tire.

How wide is a 305/70R18 tire?

A 305/70R18 tire has a width of approximately 12 inches (305 millimeters). The width of the tire is the first number in the tire size designation, which in this case is “305”. It’s important to note that the actual width of the tire may vary slightly depending on the brand and model of the tire, and the width may also be affected by the amount of air pressure in the tire.

Alternate 305/70R18 Replacement Tire Sizes

Upsizing your wheels or tires? Replacement tires must be within 3% of the diametor of the original tire. The following sizes fall within that range - click on any size to see detailed info about that tire and wheel combination.

SizeDiameterWidthWheel
275/25R3035.4"900 mm30 mm
275/55R2233.9"861 mm22 mm
275/65R2034.1"866 mm20 mm
275/80R1734.3"872 mm17 mm
275/80R1835.3"897 mm18 mm
285/55R2234.4"873 mm22 mm
285/65R2034.6"878 mm20 mm
285/75R1733.9"860 mm17 mm
285/75R1834.8"885 mm18 mm
295/25R2833.8"859 mm28 mm
295/45R2434.5"876 mm24 mm
295/55R2234.8"883 mm22 mm
295/60R2033.9"862 mm20 mm
295/65R2035.1"892 mm20 mm
295/70R1834.3"871 mm18 mm
295/75R1734.4"874 mm17 mm
305/35R2634.4"874 mm26 mm
305/45R2434.8"884 mm24 mm
305/50R2234.1"865 mm22 mm
305/55R2235.2"895 mm22 mm
305/60R2034.4"874 mm20 mm
305/70R1733.9"860 mm17 mm
305/70R1834.8"885 mm18 mm
305/75R1634"864 mm16 mm
315/20R3035"888 mm30 mm
315/40R2534.9"887 mm25 mm
315/45R2435.2"894 mm24 mm
315/50R2234.4"875 mm22 mm
315/60R2034.9"886 mm20 mm
315/70R1734.4"874 mm17 mm
315/70R1835.4"899 mm18 mm
315/75R1634.6"878 mm16 mm
325/45R2435.5"902 mm24 mm
325/50R2234.8"885 mm22 mm
325/60R2035.4"898 mm20 mm
325/65R1834.6"879 mm18 mm
325/70R1735"888 mm17 mm
335/35R2635.2"894 mm26 mm
335/40R2434.6"878 mm24 mm
335/55R2034.5"876 mm20 mm
335/70R1634.5"876 mm16 mm
345/60R1834.3"871 mm18 mm
355/40R2435.2"894 mm24 mm
355/50R2034"864 mm20 mm
355/70R1635.6"904 mm16 mm
375/40R2435.8"910 mm24 mm
375/45R2235.3"897 mm22 mm
375/60R1835.7"907 mm18 mm
375/65R1635.2"894 mm16 mm
385/35R2434.6"880 mm24 mm