285/75R18 designates a tire 285 mm (11.2") wide with a sidewall 75% as tall as it is wide — about 214 mm (8.4") — mounted on a 18-inch wheel. That works out to an overall diameter of roughly 34.8", a circumference of about 109.4", and approximately 579 revolutions per mile. Exact figures vary slightly by manufacturer and tread design.
Of the 22 285/75R18 tire models we track, the most common category is all-terrain (22 models) — a good indicator of the kind of vehicles and driving this size is designed for.