Abstract: This method and apparatus for pneumatic preloading of linear bearing assemblies is based on typical slide assemblies having ball bearing sets in rolling engagement with opposed and confronting bearing races slidably joining a base and a slide member. For adjustably preloading the bearing races, at least one and preferably a plurality of flexible, laterally expanding pneumatic tubes are positioned between a solid portion of the base and an adjustable member supporting a bearing race. Air pressure is then applied to the flexible tube(s), causing it/them to expand laterally and force confronting bearing races together to preload the bearing races. The adjustable member is then tightly secured to the base and the air pressure is removed. The tube(s) are left in position in a deflated state, and can be reused to perform the same procedure should it become necessary at a later time during the life of the assembly.