I've putzed with tracked vehicle concepts, but the real things are so high maintenance
in comparison to wheeled-vehicles, plus they're slow and aren't suited to long distance
travel, that I've pretty much shelved them, except for maybe remnants of military/govt.
forces who have access to spares, or an organized group who took over such facilities
and have people who can do the work.
Wheeled vehicles make more sense for the average survivor scenario.