32.5" tall, 9.6" wide, 7.2" sidewall
A 245/75R18 tire is 32.5 inches (825 mm) tall and 9.6 inches wide. The sidewall is 75% of the width, 7.2 inches, on a 18-inch wheel, and the tire turns about 621 times per mile.
In flotation terms that is about 32.5x9.6R18, closest to the common 33x12.50R18 (33.0"). People often call it a 32-inch tire.
The size most often compared with it is 265/70R18, which is 0.1" taller (+0.4%). At an indicated 60 mph you would be doing 60.3 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 245/75R18 | |
|---|---|---|---|---|---|
| 265/70R18 | 32.6" | 10.4" | 7.3" | +0.4% | |
| 235/80R18 | 32.8" | 9.3" | 7.4" | +1.0% | |
| 255/70R18 | 32.1" | 10.0" | 7.0" | −1.3% | |
| 235/75R18 | 31.9" | 9.3" | 6.9" | −1.8% | |
| 255/75R18 | 33.1" | 10.0" | 7.5" | +1.8% | |
| 265/65R18 | 31.6" | 10.4" | 6.8" | −2.8% | |
| 245/70R18 | 31.5" | 9.6" | 6.8" | −3.0% | |
| 265/75R18 | 33.6" | 10.4" | 7.8" | +3.6% | |
| 255/80R18 | 34.1" | 10.0" | 8.0" | +4.9% | |
| 245/65R18 | 30.5" | 9.6" | 6.3" | −5.9% |
Sizes within 2% of 32.5" on 19" or 17" or 20" or 16" wheels.
| Size | Diameter | Width | Sidewall | vs 245/75R18 | |
|---|---|---|---|---|---|
| 245/70R19 | 32.5" | 9.6" | 6.8" | +0.1% | |
| 245/80R17 | 32.4" | 9.6" | 7.7" | −0.1% | |
| 265/60R20 | 32.5" | 10.4" | 6.3" | +0.2% | |
| 315/50R20 | 32.4" | 12.4" | 6.2" | −0.2% | |
| 245/85R16 | 32.4" | 9.6" | 8.2" | −0.2% | |
| 285/55R20 | 32.3" | 11.2" | 6.2" | −0.4% |
Actual speed when the speedometer is calibrated for 245/75R18.
| Speedometer shows | on 265/70R18 | on 235/80R18 | on 255/70R18 |
|---|---|---|---|
| 30 mph | 30.1 mph | 30.3 mph | 29.6 mph |
| 45 mph | 45.2 mph | 45.5 mph | 44.4 mph |
| 60 mph | 60.3 mph | 60.6 mph | 59.2 mph |
| 70 mph | 70.3 mph | 70.7 mph | 69.1 mph |
32.5 inches (825 mm). The sidewall is 7.2 inches.
9.6 inches (245 mm) section width, measured sidewall to sidewall.
About 32.5x9.6R18; the closest common flotation size is 33x12.50R18 at 33.0".
265/70R18 is +0.4% in diameter, within the common 3% guideline. It is 0.8" wider.