285/60R20 designates a tire 285 mm (11.2") wide with a sidewall 60% as tall as it is wide — about 171 mm (6.7") — mounted on a 20-inch wheel. That works out to an overall diameter of roughly 33.5", a circumference of about 105.1", and approximately 603 revolutions per mile. Exact figures vary slightly by manufacturer and tread design.
Of the 47 285/60R20 tire models we track, the most common category is all-terrain (39 models), followed by highway all-season truck (8) — a good indicator of the kind of vehicles and driving this size is designed for.