What does 255/40R18 mean?
255/40R18 is a tire size with the following dimensions:
- 255 is the width of the tire in millimeters. This number also indicates the appropriate width of the rim on which the tire should be mounted.
- 40 is the aspect ratio, which is the ratio of the tire's height to its width. This affects the tire's handling and ride comfort
- R indicates the tire's construction type, meaning it has a radial construction. This provides stability and precision to the tire.
- 18 is the diameter of the wheel in inches, on which the tire is to be mounted.
255/40R18 Tire Conversion
| Dimensions | Inches | Millimeters |
| Tire Diameter | 26 in | 661.2 mm |
| Section Width | 10 in | 255 mm |
| Rim Height | 18 in | 457 mm |
| Sidewall Height | 4 in | 102 mm |
| Circumference | 81.8 in | 2077.2 mm |
| Revolutions | 774.8 revs/mile | |
Not the tire size you are searching for? Try our Tire Size Calculator.
FAQ About 255/40R18 Tire
How tall is a 255/40R18 tire?
The height (or diameter) of a 255/40R18 tire is 26 inches
How wide is a 255/40R18 tire?
The width of a 255/40R18 tire is 255 mm, which is about 10 inches.
What size rim fits a 255/40R18 tire?
A 255/40R18 tire fits on a rim that is 18 inches in diameter.
What does the 40 in a 255/40R18 tire mean?
The 40 in a 255/40R18 tire refers to the aspect ratio, meaning the height of the tire's sidewall is 40% of its width.
Alternative Tire Sizes for 255/40R18
Typically, it's recommended to choose a tire with a diameter (height) within 3% of the original equipment manufacturer (OEM) tire size.
However, keep in mind that this is a general guideline and not an absolute rule.
Here are some tire sizes that are compatible with the 255/40R18:
| Tire Size | Diameter | Rim |
|---|---|---|
| 145/70R18 | 26.0″ (Equal) | 18 x n/a |
| 185/55R18 | 26.0″ (Equal) | 18 x n/a |
| 225/45R18 | 26.0″ (Equal) | 18 x 7.0-8.5 |
| 135/70R18 | 25.4″ (-2.3%) | 18 x n/a |
| 135/80R18 | 26.5″ (1.9%) | 18 x n/a |
| 145/65R18 | 25.4″ (-2.3%) | 18 x n/a |
| 155/60R18 | 25.3″ (-2.7%) | 18 x n/a |
| 155/70R18 | 26.5″ (1.9%) | 18 x n/a |
| 205/45R18 | 25.3″ (-2.7%) | 18 x 6.5-7.5 |
| 205/50R18 | 26.1″ (0.4%) | 18 x n/a |
| 215/45R18 | 25.6″ (-1.5%) | 18 x 7.0-8.0 |
| 215/50R18 | 26.5″ (1.9%) | 18 x 6.0-7.5 |
| 235/40R18 | 25.4″ (-2.3%) | 18 x 8.0-9.5 |
| 235/45R18 | 26.3″ (1.2%) | 18 x 7.5-9.0 |
| 245/40R18 | 25.7″ (-1.2%) | 18 x 8.0-9.5 |
| 245/45R18 | 26.7″ (2.7%) | 18 x 7.5-9.0 |
| 265/35R18 | 25.3″ (-2.7%) | 18 x 9.0-10.5 |
| 265/40R18 | 26.3″ (1.2%) | 18 x 9.0-10.5 |
| 275/35R18 | 25.6″ (-1.5%) | 18 x 9.0-11.0 |
| 275/40R18 | 26.7″ (2.7%) | 18 x 9.0-11.0 |
| 285/35R18 | 25.9″ (-0.4%) | 18 x 9.5-11.0 |
| 295/35R18 | 26.1″ (0.4%) | 18 x 10.0-11.5 |
| 305/35R18 | 26.4″ (1.5%) | 18 x 10.0-12.0 |
| 315/30R18 | 25.4″ (-2.3%) | 18 x 10.5-11.5 |
| 315/35R18 | 26.7″ (2.7%) | 18 x 10.5-12.5 |
| 335/30R18 | 25.9″ (-0.4%) | 18 x 11.5-12.5 |
| 345/30R18 | 26.1″ (0.4%) | 18 x 12.0-14.0 |