305/55R20 Tire Size in Inches and Millimeters

305/55R20 tires have a diameter of 33.2" (844 mm), a tread width of 12" (305 mm), and a wheel diameter of 20" (508 mm).The sidewall of the tire is 6.6" (168 mm), and the tire's circumference is 104.2" (2650.2 mm). This means a 305/55R20 tire will make make 608 revolutions per mile, or 377 revolutions per kilometer.

305/55R20 Tire Front
12"
33.2"
305/55R20 Tire Side
Tire Circumference
104.2"
20"
6.6"
608 Revs/Mile
SpecInchesMetric
Diameter33.2"844 mm
Width12"305 mm
Wheel20"508 mm
Sidewall6.6"168 mm
Circum104.2"2650.2 mm
Revolutions608 per mile377 per km

What Does 305/55R20 Mean?

The tire size 305/55R20 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.
  • 55: 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 55% 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.
  • 20: 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 20-inch wheel.

305/55R20 tire size meaning

How To Convert 305/55R20 Into Inches

The 305/55R20 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, 55, 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 0.55, which gives us approximately 6.6 inches.

Finally, the last number in the tire size, 20, represents the diameter of the wheel rim in inches. Therefore, the tire size 305/55R20 can be expressed in inches as roughly 12 inches wide, 6.6 inches tall, and designed to fit a 20-inch wheel rim.

Frequently Asked Questions About 305/55R20 Tires

How tall is a 305/55R20 tire?

A 305/55R20 tire has an approximate height, also known as the overall diameter, of 33.2 inches (844 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 305/55R20 tire?

A 305/55R20 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 305/55R20 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
235/85R1732.8"832 mm17 mm
255/80R1733.1"840 mm17 mm
255/85R1633.1"840 mm16 mm
265/50R2232.5"825 mm22 mm
265/60R2032.5"826 mm20 mm
265/70R1832.6"829 mm18 mm
265/80R1632.7"830 mm16 mm
275/25R2833.4"849 mm28 mm
275/50R2232.9"835 mm22 mm
275/55R2233.9"861 mm22 mm
275/60R2033"838 mm20 mm
275/65R2034.1"866 mm20 mm
275/70R1833.2"843 mm18 mm
285/40R2433"838 mm24 mm
285/50R2233.3"845 mm22 mm
285/55R2032.4"822 mm20 mm
285/60R2033.5"850 mm20 mm
285/65R1832.6"827 mm18 mm
285/70R1732.8"832 mm17 mm
285/70R1833.7"857 mm18 mm
285/75R1632.8"834 mm16 mm
285/75R1733.9"860 mm17 mm
295/25R2833.8"859 mm28 mm
295/30R2633"838 mm26 mm
295/40R2433.3"846 mm24 mm
295/45R2232.5"825 mm22 mm
295/50R2233.7"855 mm22 mm
295/55R2032.8"832 mm20 mm
295/60R2033.9"862 mm20 mm
295/65R1833.1"841 mm18 mm
295/70R1733.3"846 mm17 mm
295/75R1633.4"848 mm16 mm
305/30R2633.2"844 mm26 mm
305/35R2432.4"824 mm24 mm
305/40R2332.6"828 mm23 mm
305/40R2433.6"854 mm24 mm
305/45R2232.8"833 mm22 mm
305/50R2234.1"865 mm22 mm
305/55R2033.2"844 mm20 mm
305/60R1832.4"823 mm18 mm
305/65R1732.6"828 mm17 mm
305/65R1833.6"853 mm18 mm
305/70R1632.8"834 mm16 mm
305/70R1733.9"860 mm17 mm
305/75R1634"864 mm16 mm
315/35R2432.7"830 mm24 mm
315/45R2233.2"843 mm22 mm
315/50R2032.4"824 mm20 mm
315/70R1532.4"823 mm15 mm
315/70R1633.4"848 mm16 mm
325/40R2232.2"819 mm22 mm
325/45R2233.5"851 mm22 mm
325/50R2032.8"834 mm20 mm
325/60R1833.3"847 mm18 mm
355/40R2233.2"843 mm22 mm
355/50R2034"864 mm20 mm
375/45R2033.3"846 mm20 mm
375/50R1832.8"833 mm18 mm