285/40R18 Tire Size in Inches and Millimeters
285/40R18 tires have a diameter of 27" (685 mm), a tread width of 11.2" (285 mm), and a wheel diameter of 18" (457.2 mm).The sidewall of the tire is 4.5" (114 mm), and the tire's circumference is 84.8" (2150.9 mm). This means a 285/40R18 tire will make make 747 revolutions per mile, or 465 revolutions per kilometer.
11.2"
27"
84.8"
18"
4.5"
747 Revs/Mile
| Spec | Inches | Metric |
|---|---|---|
| Diameter | 27" | 685 mm |
| Width | 11.2" | 285 mm |
| Wheel | 18" | 457.2 mm |
| Sidewall | 4.5" | 114 mm |
| Circum | 84.8" | 2150.9 mm |
| Revolutions | 747 per mile | 465 per km |
What Does 285/40R18 Mean?
The tire size 285/40R18 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.
- 40: 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 40% 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.
How To Convert 285/40R18 Into Inches
The 285/40R18 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, 40, 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 0.40, which gives us approximately 4.5 inches.
Finally, the last number in the tire size, 18, represents the diameter of the wheel rim in inches. Therefore, the tire size 285/40R18 can be expressed in inches as roughly 11.2 inches wide, 4.5 inches tall, and designed to fit a 18-inch wheel rim.
Frequently Asked Questions About 285/40R18 Tires
How tall is a 285/40R18 tire?
A 285/40R18 tire has an approximate height, also known as the overall diameter, of 27 inches (685 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 285/40R18 tire?
A 285/40R18 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 285/40R18 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.
| Size | Diameter | Width | Wheel |
|---|---|---|---|
| 135/70R19 | 26.5" | 673 mm | 19 mm |
| 135/80R18 | 26.5" | 673 mm | 18 mm |
| 135/90R17 | 26.6" | 676 mm | 17 mm |
| 145/60R20 | 26.9" | 682 mm | 20 mm |
| 145/65R20 | 27.4" | 696 mm | 20 mm |
| 145/80R18 | 27.1" | 689 mm | 18 mm |
| 145/85R18 | 27.7" | 703 mm | 18 mm |
| 145/90R16 | 26.3" | 668 mm | 16 mm |
| 145/90R17 | 27.3" | 694 mm | 17 mm |
| 155/60R20 | 27.3" | 694 mm | 20 mm |
| 155/70R18 | 26.6" | 675 mm | 18 mm |
| 155/70R19 | 27.6" | 701 mm | 19 mm |
| 155/80R17 | 26.8" | 680 mm | 17 mm |
| 155/80R18 | 27.8" | 705 mm | 18 mm |
| 155/90R16 | 27" | 686 mm | 16 mm |
| 165/70R18 | 27.1" | 689 mm | 18 mm |
| 165/80R16 | 26.4" | 670 mm | 16 mm |
| 165/80R17 | 27.4" | 696 mm | 17 mm |
| 175/55R20 | 27.6" | 700 mm | 20 mm |
| 175/60R19 | 27.3" | 693 mm | 19 mm |
| 175/75R16 | 26.3" | 668 mm | 16 mm |
| 175/80R16 | 27" | 686 mm | 16 mm |
| 185/75R16 | 26.9" | 684 mm | 16 mm |
| 185/80R15 | 26.7" | 677 mm | 15 mm |
| 195/50R20 | 27.7" | 704 mm | 20 mm |
| 195/75R15 | 26.5" | 673 mm | 15 mm |
| 195/75R16 | 27.5" | 698 mm | 16 mm |
| 195/80R14 | 26.3" | 668 mm | 14 mm |
| 195/80R15 | 27.3" | 693 mm | 15 mm |
| 205/55R18 | 26.9" | 683 mm | 18 mm |
| 205/60R17 | 26.7" | 678 mm | 17 mm |
| 205/60R18 | 27.7" | 703 mm | 18 mm |
| 205/65R16 | 26.5" | 672 mm | 16 mm |
| 205/65R17 | 27.5" | 698 mm | 17 mm |
| 205/70R15 | 26.3" | 669 mm | 15 mm |
| 205/70R16 | 27.3" | 694 mm | 16 mm |
| 205/75R15 | 27.1" | 689 mm | 15 mm |
| 215/45R20 | 27.6" | 702 mm | 20 mm |
| 215/50R18 | 26.5" | 673 mm | 18 mm |
| 215/55R17 | 26.3" | 668 mm | 17 mm |
| 215/55R18 | 27.3" | 693 mm | 18 mm |
| 215/60R17 | 27.2" | 690 mm | 17 mm |
| 215/65R16 | 27" | 686 mm | 16 mm |
| 215/70R15 | 26.9" | 683 mm | 15 mm |
| 215/75R14 | 26.7" | 678 mm | 14 mm |
| 215/75R15 | 27.7" | 703 mm | 15 mm |
| 225/30R22 | 27.4" | 695 mm | 22 mm |
| 225/35R20 | 26.2" | 666 mm | 20 mm |
| 225/40R20 | 27.1" | 688 mm | 20 mm |
| 225/45R19 | 27" | 685 mm | 19 mm |
| 225/50R18 | 26.9" | 683 mm | 18 mm |
| 225/55R17 | 26.8" | 680 mm | 17 mm |
| 225/55R18 | 27.8" | 705 mm | 18 mm |
| 225/60R16 | 26.6" | 676 mm | 16 mm |
| 225/60R17 | 27.6" | 702 mm | 17 mm |
| 225/65R15 | 26.5" | 673 mm | 15 mm |
| 225/65R16 | 27.5" | 698 mm | 16 mm |
| 225/70R14 | 26.5" | 672 mm | 14 mm |
| 225/70R15 | 27.4" | 697 mm | 15 mm |
| 225/75R14 | 27.3" | 694 mm | 14 mm |
| 235/30R21 | 26.6" | 675 mm | 21 mm |
| 235/30R22 | 27.6" | 701 mm | 22 mm |
| 235/35R20 | 26.5" | 672 mm | 20 mm |
| 235/35R21 | 27.4" | 697 mm | 21 mm |
| 235/40R19 | 26.4" | 671 mm | 19 mm |
| 235/40R20 | 27.4" | 696 mm | 20 mm |
| 235/45R18 | 26.3" | 669 mm | 18 mm |
| 235/45R19 | 27.4" | 695 mm | 19 mm |
| 235/50R17 | 26.3" | 668 mm | 17 mm |
| 235/50R18 | 27.3" | 693 mm | 18 mm |
| 235/55R17 | 27.2" | 690 mm | 17 mm |
| 235/60R16 | 27.1" | 688 mm | 16 mm |
| 235/65R15 | 27" | 687 mm | 15 mm |
| 235/70R14 | 27" | 686 mm | 14 mm |
| 240/55R16 | 26.4" | 670 mm | 16 mm |
| 245/30R21 | 26.8" | 681 mm | 21 mm |
| 245/35R20 | 26.8" | 680 mm | 20 mm |
| 245/35R21 | 27.8" | 705 mm | 21 mm |
| 245/40R19 | 26.7" | 679 mm | 19 mm |
| 245/40R20 | 27.7" | 704 mm | 20 mm |
| 245/45R18 | 26.7" | 677 mm | 18 mm |
| 245/45R19 | 27.7" | 703 mm | 19 mm |
| 245/50R17 | 26.7" | 678 mm | 17 mm |
| 245/50R18 | 27.7" | 703 mm | 18 mm |
| 245/55R16 | 26.6" | 676 mm | 16 mm |
| 245/55R17 | 27.6" | 702 mm | 17 mm |
| 245/60R15 | 26.6" | 675 mm | 15 mm |
| 245/60R16 | 27.6" | 700 mm | 16 mm |
| 245/65R15 | 27.5" | 699 mm | 15 mm |
| 245/70R14 | 27.6" | 700 mm | 14 mm |
| 255/30R21 | 27" | 687 mm | 21 mm |
| 255/35R20 | 27" | 686 mm | 20 mm |
| 255/40R19 | 27" | 687 mm | 19 mm |
| 255/45R18 | 27" | 687 mm | 18 mm |
| 255/50R17 | 27.1" | 688 mm | 17 mm |
| 255/55R16 | 27" | 686 mm | 16 mm |
| 255/60R15 | 27" | 687 mm | 15 mm |
| 265/25R22 | 27.2" | 691 mm | 22 mm |
| 265/30R20 | 26.3" | 668 mm | 20 mm |
| 265/30R21 | 27.3" | 693 mm | 21 mm |
| 265/35R19 | 26.3" | 669 mm | 19 mm |
| 265/35R20 | 27.3" | 694 mm | 20 mm |
| 265/40R18 | 26.3" | 669 mm | 18 mm |
| 265/40R19 | 27.4" | 695 mm | 19 mm |
| 265/45R18 | 27.4" | 695 mm | 18 mm |
| 265/50R16 | 26.5" | 672 mm | 16 mm |
| 265/60R14 | 26.5" | 674 mm | 14 mm |
| 265/60R15 | 27.5" | 699 mm | 15 mm |
| 275/25R21 | 26.4" | 671 mm | 21 mm |
| 275/25R22 | 27.4" | 697 mm | 22 mm |
| 275/30R20 | 26.5" | 674 mm | 20 mm |
| 275/30R21 | 27.5" | 699 mm | 21 mm |
| 275/35R19 | 26.6" | 675 mm | 19 mm |
| 275/35R20 | 27.6" | 700 mm | 20 mm |
| 275/40R18 | 26.7" | 677 mm | 18 mm |
| 275/40R19 | 27.7" | 703 mm | 19 mm |
| 275/45R18 | 27.8" | 705 mm | 18 mm |
| 275/50R16 | 26.9" | 682 mm | 16 mm |
| 275/55R15 | 26.9" | 683 mm | 15 mm |
| 275/60R14 | 27" | 686 mm | 14 mm |
| 285/25R22 | 27.6" | 701 mm | 22 mm |
| 285/30R20 | 26.8" | 680 mm | 20 mm |
| 285/30R21 | 27.8" | 705 mm | 21 mm |
| 285/35R19 | 26.9" | 683 mm | 19 mm |
| 285/40R18 | 27" | 685 mm | 18 mm |
| 285/50R15 | 26.3" | 667 mm | 15 mm |
| 295/25R21 | 26.8" | 681 mm | 21 mm |
| 295/30R20 | 27" | 686 mm | 20 mm |
| 295/35R19 | 27.1" | 689 mm | 19 mm |
| 295/40R17 | 26.3" | 668 mm | 17 mm |
| 295/40R18 | 27.3" | 693 mm | 18 mm |
| 295/45R17 | 27.5" | 698 mm | 17 mm |
| 295/50R15 | 26.7" | 677 mm | 15 mm |
| 295/50R16 | 27.6" | 702 mm | 16 mm |
| 295/55R15 | 27.8" | 705 mm | 15 mm |
| 305/25R21 | 27" | 685 mm | 21 mm |
| 305/30R19 | 26.3" | 667 mm | 19 mm |
| 305/30R20 | 27.2" | 692 mm | 20 mm |
| 305/35R18 | 26.4" | 671 mm | 18 mm |
| 305/35R19 | 27.4" | 697 mm | 19 mm |
| 305/40R18 | 27.6" | 701 mm | 18 mm |
| 305/50R15 | 27" | 687 mm | 15 mm |
| 315/25R20 | 26.2" | 666 mm | 20 mm |
| 315/30R19 | 26.5" | 673 mm | 19 mm |
| 315/30R20 | 27.5" | 698 mm | 20 mm |
| 315/35R18 | 26.7" | 677 mm | 18 mm |
| 315/35R19 | 27.7" | 703 mm | 19 mm |
| 315/45R16 | 27.2" | 690 mm | 16 mm |
| 325/25R20 | 26.4" | 670 mm | 20 mm |
| 325/25R21 | 27.4" | 695 mm | 21 mm |
| 325/30R19 | 26.7" | 679 mm | 19 mm |
| 325/30R20 | 27.7" | 704 mm | 20 mm |
| 325/35R18 | 27" | 685 mm | 18 mm |
| 335/25R20 | 26.6" | 676 mm | 20 mm |
| 335/30R19 | 27" | 685 mm | 19 mm |
| 335/35R17 | 26.2" | 666 mm | 17 mm |
| 345/25R20 | 26.8" | 680 mm | 20 mm |
| 345/30R18 | 26.2" | 665 mm | 18 mm |
| 345/30R19 | 27.2" | 691 mm | 19 mm |
| 345/35R18 | 27.5" | 699 mm | 18 mm |
| 355/30R19 | 27.4" | 697 mm | 19 mm |
| 355/40R16 | 27.2" | 690 mm | 16 mm |
| 375/20R21 | 26.9" | 683 mm | 21 mm |