265/40R18 Tire Size in Inches and Millimeters
265/40R18 tires have a diameter of 26.3" (669 mm), a tread width of 10.4" (265 mm), and a wheel diameter of 18" (457.2 mm).The sidewall of the tire is 4.2" (106 mm), and the tire's circumference is 82.6" (2100.7 mm). This means a 265/40R18 tire will make make 767 revolutions per mile, or 476 revolutions per kilometer.



Spec | Inches | Metric |
---|---|---|
Diameter | 26.3" | 669 mm |
Width | 10.4" | 265 mm |
Wheel | 18" | 457.2 mm |
Sidewall | 4.2" | 106 mm |
Circum | 82.6" | 2100.7 mm |
Revolutions | 767 per mile | 476 per km |
What Does 265/40R18 Mean?
The tire size 265/40R18 is a common size used on many trucks, SUVs, and other larger vehicles.
Here is what each part of the size designation represents:
- 265: This number represents the width of the tire in millimeters. In this case, the tire is 265 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 265/40R18 Into Inches
The 265/40R18 conversion is fairly simple. The first number in the tire size, 265, represents the width of the tire in millimeters. To convert this to inches, we divide 265 by 25.4 (since there are 25.4 millimeters in an inch). This gives us approximately 10.4 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 10.4 by 0.40, which gives us approximately 4.2 inches.
Finally, the last number in the tire size, 18, represents the diameter of the wheel rim in inches. Therefore, the tire size 265/40R18 can be expressed in inches as roughly 10.4 inches wide, 4.2 inches tall, and designed to fit a 18-inch wheel rim.
Frequently Asked Questions About 265/40R18 Tires
How tall is a 265/40R18 tire?
A 265/40R18 tire has an approximate height, also known as the overall diameter, of 26.3 inches (669 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 265/40R18 tire?
A 265/40R18 tire has a width of approximately 10.4 inches (265 millimeters). The width of the tire is the first number in the tire size designation, which in this case is “265”. 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.Understanding Tire Speed Ratings
When choosing the right tires for your vehicle, understanding the speed rating is crucial. But what exactly is a speed rating, and why does it matter?What is a Tire Speed Rating?
A tire's speed rating indicates the maximum speed a tire can safely sustain over time. It's a manufacturer's assurance of tire performance, marked by a letter on the tire's sidewall. This rating is determined under controlled laboratory conditions and is part of a broader standard established by industry entities like the European Tyre and Rim Technical Organisation (ETRTO) and the U.S. Department of Transportation.Common Speed Ratings Explained
- P-Rated: Up to 94 mph - Suitable for smaller sedans or light-duty vehicles.
- Q-Rated: Up to 100 mph - Often found on SUVs and light trucks with consistent highway use.
- R-Rated: Up to 106 mph - Typically for medium-duty trucks and vans.
- S-Rated: Up to 112 mph - Common for family sedans and larger vehicles with moderate performance.
- T-Rated: Up to 118 mph - Optimal for family vehicles, including minivans and some coupes.
Why is the Speed Rating Important?
The speed rating is not just about how fast you can legally drive; it's about safety and performance:- Ensures Safety: It guarantees that the tire can handle certain speeds without overheating and failing, which can prevent blowouts.
- Optimizes Performance: Higher ratings often indicate better handling characteristics, important for maintaining vehicle stability.
- Legal and Insurance Considerations: Matching the speed rating suggested by your vehicle manufacturer can be essential for insurance and warranty purposes.
Alternate 265/40R18 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 |
---|---|---|---|
115/95R17 | 25.6" | 650 mm | 17 mm |
125/70R19 | 25.9" | 659 mm | 19 mm |
135/70R19 | 26.5" | 673 mm | 19 mm |
135/80R18 | 26.5" | 673 mm | 18 mm |
135/90R16 | 25.6" | 650 mm | 16 mm |
135/90R17 | 26.6" | 676 mm | 17 mm |
145/60R20 | 26.9" | 682 mm | 20 mm |
145/70R18 | 26" | 661 mm | 18 mm |
145/80R17 | 26.1" | 664 mm | 17 mm |
145/80R18 | 27.1" | 689 mm | 18 mm |
145/90R16 | 26.3" | 668 mm | 16 mm |
155/70R17 | 25.6" | 650 mm | 17 mm |
155/70R18 | 26.6" | 675 mm | 18 mm |
155/80R16 | 25.7" | 654 mm | 16 mm |
155/80R17 | 26.8" | 680 mm | 17 mm |
155/90R16 | 27" | 686 mm | 16 mm |
165/70R17 | 26.1" | 664 mm | 17 mm |
165/70R18 | 27.1" | 689 mm | 18 mm |
165/80R16 | 26.4" | 670 mm | 16 mm |
175/75R16 | 26.3" | 668 mm | 16 mm |
175/80R16 | 27" | 686 mm | 16 mm |
185/55R18 | 26" | 661 mm | 18 mm |
185/60R17 | 25.7" | 654 mm | 17 mm |
185/75R16 | 26.9" | 684 mm | 16 mm |
185/80R14 | 25.7" | 652 mm | 14 mm |
185/80R15 | 26.7" | 677 mm | 15 mm |
195/65R16 | 26" | 660 mm | 16 mm |
195/70R15 | 25.8" | 655 mm | 15 mm |
195/75R15 | 26.5" | 673 mm | 15 mm |
195/80R14 | 26.3" | 668 mm | 14 mm |
205/50R18 | 26.1" | 663 mm | 18 mm |
205/55R17 | 25.9" | 658 mm | 17 mm |
205/55R18 | 26.9" | 683 mm | 18 mm |
205/60R16 | 25.7" | 652 mm | 16 mm |
205/60R17 | 26.7" | 678 mm | 17 mm |
205/65R16 | 26.5" | 672 mm | 16 mm |
205/70R15 | 26.3" | 669 mm | 15 mm |
205/75R14 | 26.1" | 664 mm | 14 mm |
205/75R15 | 27.1" | 689 mm | 15 mm |
215/40R19 | 25.8" | 655 mm | 19 mm |
215/45R18 | 25.6" | 651 mm | 18 mm |
215/50R18 | 26.5" | 673 mm | 18 mm |
215/55R17 | 26.3" | 668 mm | 17 mm |
215/60R16 | 26.1" | 664 mm | 16 mm |
215/65R15 | 26" | 661 mm | 15 mm |
215/65R16 | 27" | 686 mm | 16 mm |
215/70R14 | 25.9" | 658 mm | 14 mm |
215/70R15 | 26.9" | 683 mm | 15 mm |
215/75R14 | 26.7" | 678 mm | 14 mm |
225/35R20 | 26.2" | 666 mm | 20 mm |
225/40R19 | 26.1" | 663 mm | 19 mm |
225/40R20 | 27.1" | 688 mm | 20 mm |
225/45R18 | 25.9" | 659 mm | 18 mm |
225/45R19 | 27" | 685 mm | 19 mm |
225/50R17 | 25.9" | 658 mm | 17 mm |
225/50R18 | 26.9" | 683 mm | 18 mm |
225/55R16 | 25.7" | 654 mm | 16 mm |
225/55R17 | 26.8" | 680 mm | 17 mm |
225/60R15 | 25.6" | 651 mm | 15 mm |
225/60R16 | 26.6" | 676 mm | 16 mm |
225/65R15 | 26.5" | 673 mm | 15 mm |
225/70R14 | 26.5" | 672 mm | 14 mm |
235/30R20 | 25.6" | 650 mm | 20 mm |
235/30R21 | 26.6" | 675 mm | 21 mm |
235/35R20 | 26.5" | 672 mm | 20 mm |
235/40R19 | 26.4" | 671 mm | 19 mm |
235/45R18 | 26.3" | 669 mm | 18 mm |
235/50R17 | 26.3" | 668 mm | 17 mm |
235/55R16 | 26.1" | 664 mm | 16 mm |
235/60R15 | 26.1" | 663 mm | 15 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 |
245/30R20 | 25.8" | 656 mm | 20 mm |
245/30R21 | 26.8" | 681 mm | 21 mm |
245/35R19 | 25.8" | 655 mm | 19 mm |
245/35R20 | 26.8" | 680 mm | 20 mm |
245/40R18 | 25.7" | 653 mm | 18 mm |
245/40R19 | 26.7" | 679 mm | 19 mm |
245/45R17 | 25.7" | 652 mm | 17 mm |
245/45R18 | 26.7" | 677 mm | 18 mm |
245/50R16 | 25.7" | 652 mm | 16 mm |
245/50R17 | 26.7" | 678 mm | 17 mm |
245/55R16 | 26.6" | 676 mm | 16 mm |
245/60R14 | 25.6" | 650 mm | 14 mm |
245/60R15 | 26.6" | 675 mm | 15 mm |
255/30R20 | 26.1" | 662 mm | 20 mm |
255/30R21 | 27" | 687 mm | 21 mm |
255/35R19 | 26" | 661 mm | 19 mm |
255/35R20 | 27" | 686 mm | 20 mm |
255/40R18 | 26" | 661 mm | 18 mm |
255/40R19 | 27" | 687 mm | 19 mm |
255/45R17 | 26.1" | 662 mm | 17 mm |
255/45R18 | 27" | 687 mm | 18 mm |
255/50R16 | 26.1" | 662 mm | 16 mm |
255/50R17 | 27.1" | 688 mm | 17 mm |
255/55R15 | 26" | 661 mm | 15 mm |
255/55R16 | 27" | 686 mm | 16 mm |
255/60R14 | 26.1" | 662 mm | 14 mm |
255/60R15 | 27" | 687 mm | 15 mm |
265/30R20 | 26.3" | 668 mm | 20 mm |
265/35R19 | 26.3" | 669 mm | 19 mm |
265/40R18 | 26.3" | 669 mm | 18 mm |
265/50R16 | 26.5" | 672 mm | 16 mm |
265/60R14 | 26.5" | 674 mm | 14 mm |
275/25R21 | 26.4" | 671 mm | 21 mm |
275/30R19 | 25.6" | 649 mm | 19 mm |
275/30R20 | 26.5" | 674 mm | 20 mm |
275/35R18 | 25.6" | 649 mm | 18 mm |
275/35R19 | 26.6" | 675 mm | 19 mm |
275/40R17 | 25.7" | 652 mm | 17 mm |
275/40R18 | 26.7" | 677 mm | 18 mm |
275/45R16 | 25.7" | 654 mm | 16 mm |
275/50R15 | 25.9" | 657 mm | 15 mm |
275/50R16 | 26.9" | 682 mm | 16 mm |
275/55R15 | 26.9" | 683 mm | 15 mm |
275/60R14 | 27" | 686 mm | 14 mm |
285/25R20 | 25.6" | 650 mm | 20 mm |
285/30R19 | 25.8" | 655 mm | 19 mm |
285/30R20 | 26.8" | 680 mm | 20 mm |
285/35R18 | 25.9" | 657 mm | 18 mm |
285/35R19 | 26.9" | 683 mm | 19 mm |
285/40R17 | 26" | 660 mm | 17 mm |
285/40R18 | 27" | 685 mm | 18 mm |
285/50R15 | 26.3" | 667 mm | 15 mm |
295/25R20 | 25.8" | 656 mm | 20 mm |
295/25R21 | 26.8" | 681 mm | 21 mm |
295/30R19 | 26" | 661 mm | 19 mm |
295/30R20 | 27" | 686 mm | 20 mm |
295/35R18 | 26.1" | 663 mm | 18 mm |
295/35R19 | 27.1" | 689 mm | 19 mm |
295/40R17 | 26.3" | 668 mm | 17 mm |
295/50R15 | 26.7" | 677 mm | 15 mm |
305/25R20 | 26" | 660 mm | 20 mm |
305/25R21 | 27" | 685 mm | 21 mm |
305/30R19 | 26.3" | 667 mm | 19 mm |
305/35R18 | 26.4" | 671 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 |
315/35R17 | 25.7" | 652 mm | 17 mm |
315/35R18 | 26.7" | 677 mm | 18 mm |
315/40R16 | 25.9" | 658 mm | 16 mm |
325/25R20 | 26.4" | 670 mm | 20 mm |
325/30R19 | 26.7" | 679 mm | 19 mm |
325/35R18 | 27" | 685 mm | 18 mm |
335/25R19 | 25.6" | 651 mm | 19 mm |
335/25R20 | 26.6" | 676 mm | 20 mm |
335/30R18 | 25.9" | 659 mm | 18 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 |
355/25R19 | 26" | 661 mm | 19 mm |
375/20R21 | 26.9" | 683 mm | 21 mm |