A mobile robotic floor-cleaning device with wheels that may be expanded or contracted to suit various needs by rotating an inner shaft within the main housing of each wheel relative to the main housing. A series of rollers form the circumference of the wheels, and are connected to the inner shaft via a set of spokes. Rotation of the inner shaft relative to the main housing causes the spokes to pull the rollers in or push them out, changing the diameter and circumference of the wheel.