285/45R21 Tire Size in Inches and Millimeters

285/45R21 tires have a diameter of 31.1" (789 mm), a tread width of 11.2" (285 mm), and a wheel diameter of 21" (533.4 mm).The sidewall of the tire is 5" (128 mm), and the tire's circumference is 97.7" (2477.5 mm). This means a 285/45R21 tire will make make 649 revolutions per mile, or 404 revolutions per kilometer.

285/45R21 Tire Front
11.2"
31.1"
285/45R21 Tire Side
Tire Circumference
97.7"
21"
5"
649 Revs/Mile
SpecInchesMetric
Diameter31.1"789 mm
Width11.2"285 mm
Wheel21"533.4 mm
Sidewall5"128 mm
Circum97.7"2477.5 mm
Revolutions649 per mile404 per km

What Does 285/45R21 Mean?

The tire size 285/45R21 is a common size used on many trucks, SUVs, and other larger vehicles.

Here is what each part of the size designation represents:

  • 285: This number represents the width of the tire in millimeters. In this case, the tire is 285 millimeters wide.
  • 45: 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 45% 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.
  • 21: 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 21-inch wheel.

285/45R21 tire size meaning

How To Convert 285/45R21 Into Inches

The 285/45R21 conversion is fairly simple. The first number in the tire size, 285, represents the width of the tire in millimeters. To convert this to inches, we divide 285 by 25.4 (since there are 25.4 millimeters in an inch). This gives us approximately 11.2 inches.

The second number in the tire size, 45, represents the aspect ratio or the height of the tire as a percentage of its width. To calculate the height in inches, we multiply 11.2 by 0.45, which gives us approximately 5 inches.

Finally, the last number in the tire size, 21, represents the diameter of the wheel rim in inches. Therefore, the tire size 285/45R21 can be expressed in inches as roughly 11.2 inches wide, 5 inches tall, and designed to fit a 21-inch wheel rim.

Bridgestone Alenza Sport A/S Run-Flat SUV Tire 285/45R21 113 H Extra Load
Bridgestone Alenza Sport A/S Run-Flat SUV Tire 285/45R21 113 H Extra Load
Bridgestone Alena sport a/s raft P285/45R21 113H bsp all-season tire; Model Number: 4031; Item Package Dimension: 31.1" L x 11.0" W x 31.1" H
$465.97
Sale
HANKOOK Dynapro HP2 Plus 285/45R21 XL 113H BSW
HANKOOK Dynapro HP2 Plus 285/45R21 XL 113H BSW
Straight 4-channel waterway resists hydroplaning and aquaplaning performance up; Package Dimensions: 31 H x 31 L x 12.1 W (inches)
$288.21
Pirelli Tires P ZERO PZ4 (RUN FLAT) 285X45R21 Tire - Summer, Performance,Run Flat
Pirelli Tires P ZERO PZ4 (RUN FLAT) 285X45R21 Tire - Summer, Performance,Run Flat
Treadlife: N/A; Season: Summer; Performance: High Performance; Car Type: Truck/SUV; Load Range XL, 4-Ply Rated, 4-PR
Bridgestone Alenza Sport A/S SUV Touring All-Season Tire 285/45R21 113 H Extra Load
Bridgestone Alenza Sport A/S SUV Touring All-Season Tire 285/45R21 113 H Extra Load
All season performance; Model Number: 4023; Item Package Dimension: 31.1" L x 8.4" W x 31.1" H
$425.83

Frequently Asked Questions About 285/45R21 Tires

How tall is a 285/45R21 tire?

A 285/45R21 tire has an approximate height, also known as the overall diameter, of 31.1 inches (789 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 285/45R21 tire?

A 285/45R21 tire has a width of approximately 11.2 inches (285 millimeters). The width of the tire is the first number in the tire size designation, which in this case is “285”. 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 285/45R21 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
165/90R1930.7"781 mm19 mm
175/90R1830.4"773 mm18 mm
215/85R1630.4"772 mm16 mm
225/75R1730.3"770 mm17 mm
225/75R1831.3"795 mm18 mm
225/85R1631"788 mm16 mm
225/90R1632"812 mm16 mm
235/55R2030.2"766 mm20 mm
235/65R1931.1"789 mm19 mm
235/70R1831"787 mm18 mm
235/75R1730.9"784 mm17 mm
235/75R1831.9"809 mm18 mm
235/80R1630.8"782 mm16 mm
235/80R1731.8"808 mm17 mm
235/85R1631.7"806 mm16 mm
245/60R2031.6"802 mm20 mm
245/65R1830.5"775 mm18 mm
245/70R1730.6"776 mm17 mm
245/70R1831.5"801 mm18 mm
245/75R1630.5"774 mm16 mm
245/75R1731.5"800 mm17 mm
255/45R2231.1"789 mm22 mm
255/50R2131.1"789 mm21 mm
255/55R2031"788 mm20 mm
255/60R1931.1"789 mm19 mm
255/65R1831.1"789 mm18 mm
255/70R1731.1"790 mm17 mm
265/40R2230.4"771 mm22 mm
265/45R2130.4"771 mm21 mm
265/45R2231.4"797 mm22 mm
265/50R2030.5"774 mm20 mm
265/55R1930.5"775 mm19 mm
265/60R1830.5"775 mm18 mm
265/65R1730.6"776 mm17 mm
265/65R1831.5"801 mm18 mm
265/70R1630.6"778 mm16 mm
265/70R1731.7"804 mm17 mm
265/75R1530.7"779 mm15 mm
265/75R1631.7"804 mm16 mm
275/25R2631.4"798 mm26 mm
275/30R2430.6"776 mm24 mm
275/40R2230.7"779 mm22 mm
275/40R2331.7"804 mm23 mm
275/45R2130.7"781 mm21 mm
275/45R2231.8"807 mm22 mm
275/50R2030.9"784 mm20 mm
275/50R2131.9"809 mm21 mm
275/55R1930.9"785 mm19 mm
275/55R2031.9"810 mm20 mm
275/60R1831"787 mm18 mm
275/65R1731.1"790 mm17 mm
275/70R1530.2"767 mm15 mm
275/70R1631.2"792 mm16 mm
285/30R2430.8"782 mm24 mm
285/35R2330.9"784 mm23 mm
285/35R2431.9"810 mm24 mm
285/40R2231"787 mm22 mm
285/40R2332"812 mm23 mm
285/45R2131.1"789 mm21 mm
285/50R2031.3"794 mm20 mm
285/55R1830.4"771 mm18 mm
285/55R1931.4"797 mm19 mm
285/60R1730.5"774 mm17 mm
285/60R1831.5"799 mm18 mm
285/65R1630.6"776 mm16 mm
285/65R1731.6"802 mm17 mm
285/70R1530.7"781 mm15 mm
285/70R1631.7"806 mm16 mm
295/25R2631.8"808 mm26 mm
295/30R2431"788 mm24 mm
295/35R2331.1"790 mm23 mm
295/40R2130.3"769 mm21 mm
295/40R2231.3"795 mm22 mm
295/45R2030.5"774 mm20 mm
295/50R2031.7"804 mm20 mm
295/65R1631.1"790 mm16 mm
305/25R2632"812 mm26 mm
305/35R2230.4"773 mm22 mm
305/35R2331.4"798 mm23 mm
305/40R2231.6"803 mm22 mm
305/45R2030.8"782 mm20 mm
305/60R1731.4"798 mm17 mm
305/70R1531.9"809 mm15 mm
315/30R2431.5"800 mm24 mm
315/35R2230.7"779 mm22 mm
315/40R2130.9"785 mm21 mm
325/30R2330.7"780 mm23 mm
325/35R2231"787 mm22 mm
325/35R2332"812 mm23 mm
325/40R2131.2"793 mm21 mm
325/60R1530.4"771 mm15 mm
335/30R2432"812 mm24 mm
345/55R1630.9"786 mm16 mm
345/55R1732"812 mm17 mm
355/25R2431"788 mm24 mm
405/25R2432"812 mm24 mm