25.0" tall, 10.0" wide, 4.0" sidewall
A 255/40R17 tire is 25.0 inches (636 mm) tall and 10.0 inches wide. The sidewall is 40% of the width, 4.0 inches, on a 17-inch wheel, and the tire turns about 806 times per mile.
In flotation terms that is about 25.0x10.0R17. People often call it a 25-inch tire.
The size most often compared with it is 275/40R17, which is 0.6" taller (+2.5%). At an indicated 60 mph you would be doing 61.5 mph on it.
| Current | New | Difference |
|---|
| Shows | Actual speed |
|---|
Same 17" wheel, within 20 mm of width and 10 points of aspect ratio.
| Size | Diameter | Width | Sidewall | vs 255/40R17 | |
|---|---|---|---|---|---|
| 245/40R17 | 24.7" | 9.6" | 3.9" | −1.3% | |
| 275/35R17 | 24.6" | 10.8" | 3.8" | −1.8% | |
| 235/40R17 | 24.4" | 9.3" | 3.7" | −2.5% | |
| 275/40R17 | 25.7" | 10.8" | 4.3" | +2.5% | compare |
| 255/45R17 | 26.0" | 10.0" | 4.5" | +4.0% | |
| 265/50R17 | 27.4" | 10.4" | 5.2" | +9.6% | |
| 275/50R17 | 27.8" | 10.8" | 5.4" | +11.2% |
Sizes within 2% of 25.0" on 18" or 15" or 16" wheels.
| Size | Diameter | Width | Sidewall | vs 255/40R17 | |
|---|---|---|---|---|---|
| 255/35R18 | 25.0" | 10.0" | 3.5" | −0.0% | |
| 295/30R18 | 25.0" | 11.6" | 3.5" | −0.3% | |
| 215/60R15 | 25.2" | 8.5" | 5.1" | +0.5% | |
| 225/50R16 | 24.9" | 8.9" | 4.4" | −0.7% | |
| 305/30R18 | 25.2" | 12.0" | 3.6" | +0.7% | |
| 265/35R18 | 25.3" | 10.4" | 3.7" | +1.1% |
Actual speed when the speedometer is calibrated for 255/40R17.
| Speedometer shows | on 275/40R17 | on 245/40R17 | on 275/35R17 |
|---|---|---|---|
| 30 mph | 30.8 mph | 29.6 mph | 29.5 mph |
| 45 mph | 46.1 mph | 44.4 mph | 44.2 mph |
| 60 mph | 61.5 mph | 59.2 mph | 58.9 mph |
| 70 mph | 71.8 mph | 69.1 mph | 68.7 mph |
25.0 inches (636 mm). The sidewall is 4.0 inches.
10.0 inches (255 mm) section width, measured sidewall to sidewall.
About 25.0x10.0R17.
275/40R17 is +2.5% in diameter, within the common 3% guideline. It is 0.8" wider.