25.6" tall, 10.8" wide, 3.8" sidewall
A 275/35R18 tire is 25.6 inches (650 mm) tall and 10.8 inches wide. The sidewall is 35% of the width, 3.8 inches, on a 18-inch wheel, and the tire turns about 788 times per mile.
In flotation terms that is about 25.6x10.8R18. People often call it a 26-inch tire.
The size most often compared with it is 275/40R18, which is 1.1" taller (+4.2%). At an indicated 60 mph you would be doing 62.5 mph on it, more than the 3% change many shops use as a limit.
| 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 275/35R18 | |
|---|---|---|---|---|---|
| 265/35R18 | 25.3" | 10.4" | 3.7" | −1.1% | |
| 285/35R18 | 25.9" | 11.2" | 3.9" | +1.1% | |
| 255/40R18 | 26.0" | 10.0" | 4.0" | +1.8% | |
| 255/35R18 | 25.0" | 10.0" | 3.5" | −2.2% | |
| 295/35R18 | 26.1" | 11.6" | 4.1" | +2.2% | |
| 295/30R18 | 25.0" | 11.6" | 3.5" | −2.4% | |
| 265/40R18 | 26.3" | 10.4" | 4.2" | +3.0% | |
| 285/30R18 | 24.7" | 11.2" | 3.4" | −3.3% | |
| 275/30R18 | 24.5" | 10.8" | 3.2" | −4.2% | |
| 275/40R18 | 26.7" | 10.8" | 4.3" | +4.2% | compare |
Sizes within 2% of 25.6" on 16" or 17" or 20" wheels.
| Size | Diameter | Width | Sidewall | vs 275/35R18 | |
|---|---|---|---|---|---|
| 245/50R16 | 25.6" | 9.6" | 4.8" | +0.3% | |
| 275/40R17 | 25.7" | 10.8" | 4.3" | +0.3% | |
| 315/35R17 | 25.7" | 12.4" | 4.3" | +0.4% | |
| 225/30R20 | 25.3" | 8.9" | 2.7" | −1.0% | |
| 285/40R17 | 26.0" | 11.2" | 4.5" | +1.6% | |
| 255/45R17 | 26.0" | 10.0" | 4.5" | +1.8% |
Actual speed when the speedometer is calibrated for 275/35R18.
| Speedometer shows | on 275/40R18 | on 265/35R18 | on 285/35R18 |
|---|---|---|---|
| 30 mph | 31.3 mph | 29.7 mph | 30.3 mph |
| 45 mph | 46.9 mph | 44.5 mph | 45.5 mph |
| 60 mph | 62.5 mph | 59.4 mph | 60.6 mph |
| 70 mph | 73.0 mph | 69.2 mph | 70.8 mph |
25.6 inches (650 mm). The sidewall is 3.8 inches.
10.8 inches (275 mm) section width, measured sidewall to sidewall.
About 25.6x10.8R18.
275/40R18 is +4.2% in diameter, more than the common 3% guideline, so expect a speedometer error and check clearance. It is 0.0" wider.