I would like to add: Also, towards the end of the war, when supplies were short, some vehicles were painted with the old Dark Gray (some perhaps still around after being discontinued earlier), plus combinations of the three camo colors (yellow, red-brown, green), so it is possible to have dark gray with red stripes perhaps, in the later years (but its also possible anytime probably). Also, I think there were two colors commanders could use to augment the Dark Gray color, namely an olive green and a brown color. In the winter, whitewash was scarce usually, and tanks could be seen in the early months of the Russian campaign (and through-out the war actually) with anything from bedsheets to scribbled chalk used for snow camo. Most of the time, the vehicles shipped to the front in the established color of the time (gray or yellow), with cans of the modifying camoflage colors being dispensed haphazardly at best, with some units getting no modifying colors at all. Commanders were expected to apply the modifying colors in the field, to fit the local terrain conditions. This led to wide variations in application. The cans of color were issued in a thick paste, to be thinned down with petrol (fuel), but often, due to shortages, contaminated fuel, kerosene, or even water was used, hence the wide variations in color seen on German vehicles. In Afrika and in southern Russia, mud was applied to gray vehicles. Also, in Afrika, two shades of desert tan were used, with a "pea green" used to modify base color. I advise you to look at the series of books by Squadron called "Panzer Colors", there are three volumes.
jc1000