33.1" tall, 10.0" wide, 6.5" sidewall
A 255/65R20 tire is 33.1 inches (840 mm) tall and 10.0 inches wide. The sidewall is 65% of the width, 6.5 inches, on a 20-inch wheel, and the tire turns about 610 times per mile.
In flotation terms that is about 33.1x10.0R20, closest to the common 33x12.50R20 (33.0"). People often call it a 33-inch tire.
The size most often compared with it is 275/60R20, which is 0.1" shorter (−0.2%). At an indicated 60 mph you would be doing 59.9 mph on it.
| Current | New | Difference |
|---|
| Shows | Actual speed |
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Same 20" wheel, within 20 mm of width and 10 points of aspect ratio.
| Size | Diameter | Width | Sidewall | vs 255/65R20 | |
|---|---|---|---|---|---|
| 275/60R20 | 33.0" | 10.8" | 6.5" | −0.2% | |
| 265/65R20 | 33.6" | 10.4" | 6.8" | +1.5% | |
| 265/60R20 | 32.5" | 10.4" | 6.3" | −1.6% | |
| 255/60R20 | 32.0" | 10.0" | 6.0" | −3.0% | |
| 275/65R20 | 34.1" | 10.8" | 7.0" | +3.1% | |
| 275/55R20 | 31.9" | 10.8" | 6.0" | −3.5% | |
| 245/60R20 | 31.6" | 9.6" | 5.8" | −4.5% | |
| 265/70R20 | 34.6" | 10.4" | 7.3" | +4.7% | |
| 265/55R20 | 31.5" | 10.4" | 5.7" | −4.8% | |
| 275/70R20 | 35.2" | 10.8" | 7.6" | +6.4% |
Sizes within 2% of 33.1" on 19" or 18" or 22" wheels.
| Size | Diameter | Width | Sidewall | vs 255/65R20 | |
|---|---|---|---|---|---|
| 255/70R19 | 33.1" | 10.0" | 7.0" | +0.0% | |
| 255/75R18 | 33.1" | 10.0" | 7.5" | +0.0% | |
| 295/65R18 | 33.1" | 11.6" | 7.5" | +0.1% | |
| 33x12.50R18 | 33.0" | 12.5" | 7.5" | −0.2% | |
| 33x12.50R22 | 33.0" | 12.5" | 5.5" | −0.2% | |
| 275/70R18 | 33.2" | 10.8" | 7.6" | +0.3% |
Actual speed when the speedometer is calibrated for 255/65R20.
| Speedometer shows | on 275/60R20 | on 265/65R20 | on 265/60R20 |
|---|---|---|---|
| 30 mph | 29.9 mph | 30.5 mph | 29.5 mph |
| 45 mph | 44.9 mph | 45.7 mph | 44.3 mph |
| 60 mph | 59.9 mph | 60.9 mph | 59.0 mph |
| 70 mph | 69.9 mph | 71.1 mph | 68.9 mph |
33.1 inches (840 mm). The sidewall is 6.5 inches.
10.0 inches (255 mm) section width, measured sidewall to sidewall.
About 33.1x10.0R20; the closest common flotation size is 33x12.50R20 at 33.0".
275/60R20 is −0.2% in diameter, within the common 3% guideline. It is 0.8" wider.