A tank is an armoured fighting vehicle that came into existence during world war 1. Normally tanks have tracks/treads, but all armoured vehicles in the canon Just Cause Universe have so far had wheels. In-game they are referred to as "tanks".
Mitsubishi Heavy Industries 10式戦車 (Japan, Modern Day).
Converted from a tractor, so it's a technical tracked/threaded tractor. This is really some kind of an infantry fighting vehicle rather than a tank, because it lacks a main armament that would make it worthy of being called a proper tank.
New Zealand's "Bob Semple tank", converted from tractors. As you can see the term 'tank' is used quite loosely.