I could be wrong but I think they're rubber tracks: https://patents.google.com/patent/EP1564118A1 https://patents.google.com/patent/EP1564118A1 or something l

I could be wrong but I think they're rubber tracks: https://patents.google.com/patent/EP1564118A1 https://patents.google.com/patent/EP1564118A1 or something like: http://www.americantracktruck.com/index.php?page=track-system-information http://www.americantracktruck.com/index.php?page=track-syste... https://mattracks.co/ https://mattracks.co/ Could be the article got their terminology a bit mixed up?