The power wheelchair includes an anti-tip assembly extending from the frame. The anti-tip assembly includes a plate secured to the frame via a dampening mechanism. A first arm extends from the plate and is mounted thereto for a limited amount of relative movement. A grounding engaging wheel disposed on a distal end of the arm is urged toward the ground surface by a biasing spring interposed between the arm and the plate. As the wheelchair begins to tip, anti-tip or resistive forces are generated initially by the biasing spring. This resisting force continues in a linear fashion until relative movement between the arm and the plate ceases. Thereafter, further resistive forces are provided by the dampener as movement of the plate toward the frame is resisted in a linear fashion by the dampener.