Oregon Revised Statutes Oregon Vehicle Code § 801.194

(a) Travels on four or more pneumatic tires that are six inches or more in width and that are designed for use on wheels with a rim diameter of 14 inches or less;

(b) Is designed for or capable of cross-country travel on or immediately over land, water, sand, snow, ice, marsh, swampland or other natural terrain;

(c) Has nonstraddle seating;

(d) Has a steering wheel for steering control;

(e) Has a dry weight of 1,800 pounds or less; and

(f) Is 65 inches wide or less at its widest point.