A set of actuators can expand the wheel to its full diameter for traversing large objects and difficult terrain and retract them to a smaller diameter for moving under objects and small spaces. A series of sensors outside the wheels detect the terrain and then adjust the wheel diameter accordingly making the design both agile and strong. So much so that it's designed to move quickly while carrying a payload. If the robot is carrying too much weight, it will deflate the wheels until it can produce enough torque to move efficiently.
Think of the implications for lowrider technology: