26.3" tall, 10.4" wide, 4.2" sidewall
A 265/40R18 tire is 26.3 inches (669 mm) tall and 10.4 inches wide. The sidewall is 40% of the width, 4.2 inches, on a 18-inch wheel, and the tire turns about 765 times per mile.
In flotation terms that is about 26.3x10.4R18. People often call it a 26-inch tire.
The size most often compared with it is 255/40R18, which is 0.3" shorter (−1.2%). At an indicated 60 mph you would be doing 59.3 mph on it.
| Current | New | Difference |
|---|
| Shows | Actual speed |
|---|
Same 18" wheel, within 20 mm of width and 10 points of aspect ratio.
| Size | Diameter | Width | Sidewall | vs 265/40R18 | |
|---|---|---|---|---|---|
| 255/40R18 | 26.0" | 10.0" | 4.0" | −1.2% | |
| 275/40R18 | 26.7" | 10.8" | 4.3" | +1.2% | |
| 285/35R18 | 25.9" | 11.2" | 3.9" | −1.9% | |
| 285/40R18 | 27.0" | 11.2" | 4.5" | +2.4% | |
| 255/45R18 | 27.0" | 10.0" | 4.5" | +2.6% | |
| 275/35R18 | 25.6" | 10.8" | 3.8" | −2.9% | |
| 265/35R18 | 25.3" | 10.4" | 3.7" | −4.0% | |
| 255/35R18 | 25.0" | 10.0" | 3.5" | −5.0% | |
| 275/45R18 | 27.7" | 10.8" | 4.9" | +5.3% | |
| 285/30R18 | 24.7" | 11.2" | 3.4" | −6.1% |
Sizes within 2% of 26.3" on 17" or 19" wheels.
| Size | Diameter | Width | Sidewall | vs 265/40R18 | |
|---|---|---|---|---|---|
| 295/40R17 | 26.3" | 11.6" | 4.6" | −0.2% | |
| 305/30R19 | 26.2" | 12.0" | 3.6" | −0.5% | |
| 305/40R17 | 26.6" | 12.0" | 4.8" | +1.0% | |
| 255/45R17 | 26.0" | 10.0" | 4.5" | −1.2% | |
| 205/60R17 | 26.7" | 8.1" | 4.8" | +1.3% | |
| 285/40R17 | 26.0" | 11.2" | 4.5" | −1.4% |
Actual speed when the speedometer is calibrated for 265/40R18.
| Speedometer shows | on 255/40R18 | on 275/40R18 | on 285/35R18 |
|---|---|---|---|
| 30 mph | 29.6 mph | 30.4 mph | 29.4 mph |
| 45 mph | 44.5 mph | 45.5 mph | 44.2 mph |
| 60 mph | 59.3 mph | 60.7 mph | 58.9 mph |
| 70 mph | 69.2 mph | 70.8 mph | 68.7 mph |
26.3 inches (669 mm). The sidewall is 4.2 inches.
10.4 inches (265 mm) section width, measured sidewall to sidewall.
About 26.3x10.4R18.
255/40R18 is −1.2% in diameter, within the common 3% guideline. It is 0.4" narrower.