Wheelchairs are the basic source of movement for people with mobility disabilities, regardless of their type of drive. One of the main properties of wheelchairs, apart from the ability to generate drive, maneuverability and body support, is also stability. It depends largely on the position of the center of gravity in the wheelchair-human system. This property is very important from the point of view of the safe use of wheelchairs, especially when overcoming architectural obstacles such as curbs, stairs or hills. Currently, many models available on the market have additional protection in the form of additional support wheels that prevent the wheelchair from tipping backwards with the user. However, their use increases the weight and dimensions of the wheelchair, as well as reduces the ergonomics of use. Before posing such a problem, the authors performed a series of tests on the location of the center of gravity for various wheelchair designs. The research analyzed the displacement of the center of gravity depending on the ground inclination angle, indicating the limit parameters affecting the stability and safety of use. The obtained conclusions about stability and the calculation of the extreme position of the center of gravity in relation to balance can constitute the basis for the design of new wheelchair structures.