Tireblocks Defense is a small company out of Georgia that offers a product of the same name. It is designed as a foam, run flat insert for off-road tires and offers the tire the ability to still per from despite zero inflation. The product originated in the racing world and has been adopted by military groups for use with ATVs as well as MRZRs. There is also a motorcycle version.
Contact www.tbdefense.com for specialized applications.