255/65R17 designates a tire 255 mm (10.0") wide with a sidewall 65% as tall as it is wide — about 166 mm (6.5") — mounted on a 17-inch wheel. That works out to an overall diameter of roughly 30.1", a circumference of about 94.4", and approximately 671 revolutions per mile. Exact figures vary slightly by manufacturer and tread design.
Of the 48 255/65R17 tire models we track, the most common category is all-terrain (25 models), followed by highway all-season truck (19) — a good indicator of the kind of vehicles and driving this size is designed for.