a new twist on an old design idea, but it doesn't look like it's been mass produced yet

http://thekneeslider.com/archives/2006/01/12/hyanide-and-baal-all-terrain-motorcycles/
From 2006. Nothing since then to show that these got past the drawing board.

Back in 1937 this way prototyped, a 1937 Mercier, 1 of 3 built for the French military

http://thekneeslider.com/archives/2009/03/26/1937-front-drive-tracked-motorcycle-prototype/