I found some plaster and was able to put a few layers of both dry and wet looking mud on the tiger. The mud obliterated the nicely painted road wheels, but it did let me hide the terrible tracks that came with this model. I am really please with how it came out though, since it adds a level of realism that will look good on my kursk force.
Dark Earth Pigment + Plaster Water
AK-Interactive wet effects enamel for the wet centers
AK-Interactive kursk soil enamel flicked on using a tooth pick and a stiff brush
I am going to experiment more with mud. It might be my new favorite thing since I discovered streaking grime for vehicles!