275/60R20 designates a tire 275 mm (10.8") wide with a sidewall 60% as tall as it is wide — about 165 mm (6.5") — mounted on a 20-inch wheel. That works out to an overall diameter of roughly 33.0", a circumference of about 103.6", and approximately 611 revolutions per mile. Exact figures vary slightly by manufacturer and tread design.
Of the 107 275/60R20 tire models we track, the most common category is all-terrain (58 models), followed by highway all-season truck (28) — a good indicator of the kind of vehicles and driving this size is designed for.