Well, there are some options...
If the track is supposed to be dirty (and it is), you can spray everything dirt colour and it will reasonably go between the road wheels too, at least as far as anybody can see. Other trick would be to paint surfaces that would be hard to get when assembled with black or dark Gunze paint. Thing is lacquer thinner, Tamiya thin and stuff like that dissolve Gunze paint, so it doesn't have to be scraped away when glueing with solvent type glue. And the dark colour simulates shadow.
Let me get back to the "dirty" concept - when the tracked vehicle has wallowed in the mud for long enough (and that really isn't a very long time) everything gets dirty, especially the parts in contact with the ground. Instead of painting the model paint colour and then trying to dirty it up, I paint the model dirt colour (at least the lower half) and then on this I paint the areas where the mud was scraped away or something like that. This way painting gets easier and the vehicle looks better IMO. So for tracks I paint everything dirt colour, and then I pick up the centers of wheels with camouflage colour and the edges of tracks with steel colour (where it has been abraded away) - guide teeth surfaces, sprocket working surfaces and where it touches the track etc.
I hope the above is understandable - god luck with your tracks and have a nice day
Paweł