I haven't really thought about the 'Cons much, but surely there should be a few, what with their fondness for military vehicles.

Megatron I'm not counting - he didn't get a tank mode 'til G2 I think?

Decepticons
Blitzwing
Brawl
Overlord
Skullgrin - doesn't really have treads - but he still qualifies as a tank
Bludgeon

Is that it? Seems like there must be many more I'm missing.