28.1" tall, 13.6" wide, 4.1" sidewall
A 345/30R20 tire is 28.1 inches (715 mm) tall and 13.6 inches wide. The sidewall is 30% of the width, 4.1 inches, on a 20-inch wheel, and the tire turns about 716 times per mile.
In flotation terms that is about 28.1x13.6R20. People often call it a 28-inch tire.
The size most often compared with it is 325/35R20, which is 0.8" taller (+2.9%). At an indicated 60 mph you would be doing 61.7 mph on it.
| Current | New | Difference |
|---|
| Shows | Actual speed |
|---|
Same 20" wheel, within 20 mm of width and 10 points of aspect ratio.
| Size | Diameter | Width | Sidewall | vs 345/30R20 | |
|---|---|---|---|---|---|
| 325/35R20 | 29.0" | 12.8" | 4.5" | +2.9% |
Sizes within 2% of 28.1" on 18" or 22" wheels.
| Size | Diameter | Width | Sidewall | vs 345/30R20 | |
|---|---|---|---|---|---|
| 285/45R18 | 28.1" | 11.2" | 5.0" | −0.2% | |
| 255/50R18 | 28.0" | 10.0" | 5.0" | −0.4% | |
| 265/30R22 | 28.3" | 10.4" | 3.1" | +0.4% | |
| 265/50R18 | 28.4" | 10.4" | 5.2" | +1.0% | |
| 295/45R18 | 28.5" | 11.6" | 5.2" | +1.1% | |
| 275/45R18 | 27.7" | 10.8" | 4.9" | −1.4% |
Actual speed when the speedometer is calibrated for 345/30R20.
| Speedometer shows | on 325/35R20 |
|---|---|
| 30 mph | 30.9 mph |
| 45 mph | 46.3 mph |
| 60 mph | 61.7 mph |
| 70 mph | 72.0 mph |
28.1 inches (715 mm). The sidewall is 4.1 inches.
13.6 inches (345 mm) section width, measured sidewall to sidewall.
About 28.1x13.6R20.
325/35R20 is +2.9% in diameter, within the common 3% guideline. It is 0.8" narrower.