There are plenty in the pool but they just do not get delivered to the front during the clear weather weeks while I am atacking.
After three mud turns with my PZ divs on refit barely 250 tanks have been delivered to front line units.
I have a total of 577 med tanks in the pool just sitting there after three weeks of refitting and I need these tanks in front line units for the snow offensive.
I suspect someone might say it is better to have fewer tanks because then your mobile units will have a greater range due to less fuel needs, but blah to that

How do you get those tanks delivered?
is it because I have been using rail movement to much to move my troops about the map from army group and railing in my reinforcements which often times leave my rail capacity at just a few thousand.
I noticed in the Editor that each unit has a 'LOAD COST', how relevant is that to the AI hauling supplies and weapons to the front line? If this is subject to how much the AI can move supplies and weapons to the front then I think I will use Rail movement much less.