Wheeled vehicles, such as wheelchairs, that are adapted to traverse obstacles are provided. The wheeled vehicles include a frame, drive wheels, front anti-tip wheels positioned in front of the drive wheels and rear anti-tip wheels positioned behind the drive wheels. One exemplary vehicle includes front anti-tip wheels supported by rigid arms that are fixed to the frame and drive assemblies that are independently suspended from the frame. Another exemplary vehicle includes a linkage that links the front and rear anti-tip wheels, such that movement of one of the front or rear anti-tip wheel relative to the frame causes movement of the other wheel relative to the frame.