Just curious dave, wouldn't it be easier to model the treads in a 360 degree circle, apply a wire deformer to them, use a geometry constrain between the wire deformer to the road wheels , and then geometry constrain the road wheels to ground plane, Set up 2 sdk's on the tank treads, one to allow them to roll forwards and back when the tank group node is translated locally along the correct axis for forward in your orientation and another for the treads to rotate opposite to each other for left and right turns, so that all you have to do is then translate the tank around your scene, and maya does the rest for you?

i know the process its self is a bit more indepth, and i might have the geometry constrains backwards, it might be constrain the wire and wheels to teh ground, i don't recall off the top of my head, but...i would go that route other then use n cloth mate... just my two cents.

g-man