255/70R17 designates a tire 255 mm (10.0") wide with a sidewall 70% as tall as it is wide — about 179 mm (7.0") — mounted on a 17-inch wheel. That works out to an overall diameter of roughly 31.1", a circumference of about 97.6", and approximately 649 revolutions per mile. Exact figures vary slightly by manufacturer and tread design.
Of the 53 255/70R17 tire models we track, the most common category is all-terrain (32 models), followed by highway all-season truck (16) — a good indicator of the kind of vehicles and driving this size is designed for.