I like the mood of the images. But do you have neutral images of your tank too? Because of the dark materials of the tank combined with the dimmed light, it's difficult to give proper feedback.
I agree with Crazy_pixel. Also post wireframe shots of the tank.
The concept of the upper body and the tower seems promising (and now comes the famous) but... I'm missing some context here: Is this a futuristic game asset or some more realistic approach ? For the first i'm fine with hovering wheels/tracks and a super big main cannon. Here is what i see (quick re-model):
The red wheels are floating in midair, there are no wheel which do form the upper buldge of the chain/track. There is a weird space in the back (red wireframe cuboid).. excavators may have such kind of extension (if the wheels have some connection) but no warmachine like a tank (to fragile). And the main cannon seems to be be a bit too big at the front (on real tanks this also wight more than a ton). Just my two cents.