Hi,
I see two solutions :
- "brute force", when you can try to simulate realistically the tracks, using a big bunch of "flat boxes" joined by another big bunch of hinges, powered by rotating cylinders and "guided" by a few more cylinders. It allows some fun stuffs like the track being able to "jump of" the tank, but it will probably be -quiet- very heavy on the CPU ...
- usual physics faking
You can probably approximate each track of the tank with a few cylinders and/or spheres. You'll have to draw fakes 3D tracks by yourself, but it will be way more gentle with the framerate, way more easier to tune and probably quiet stable (way more than the first solution, at least). I think ouille did something like this in test8.c (as far as I can remember), for the physics part.
Depends on what you want, in facts !