a multiple layer foam insert replacement for a pneumatic inner tube for a tire . the multiple layer foam insert emulates the effect of air pressure , across a range of pressures , while still approaching the weight of the air filled tube . through the use of different density materials and the orientation and thickness of such materials , the desirable characteristics of the pneumatic tube structure and performance can be emulated to a high degree . this multiple layer foam insert can be produced in varying levels of quality and function through the method of extrusion of foam materials in different sizes and layering .