Observations of a warp in a gas disk in the halo of a galaxy are shown to provide limits that can be set on the tumbling motion of the halo around the disk. The numerical model of Tohline and Durisen (1982- TD) for a rotating halo sustaining a steady-state warp in a gas disk is extended to real galaxies. The analysis is restricted to a prolate spheroidal halo tumbling about one of its short principal axes. The inclination angle and the angular momentum vector are shown to have the capability of changing with the radius of the halo, while a steady-state warp will appear if the gas orbits retrograde to the direction of the halo's tumbling. The TD model is considered for orbits inside an inhomogeneous mass distribution and preferred tumbling inclinations are obtained, together with estimated tumbling rates. Applications to spiral and elliptical galaxies are discussed in terms of the tumbling period. The model is concluded to be useful for investigations of the formation of spiral galaxies.