Heheh, why dont you try doing a search, this topic has come up very often...ah what the heck, the tanks are basiclly 1/76 but are deformed so they dont really have a scale. They work find with HO (1/87) train buildings and would with 1/72 as well most likely.
I'm in the process of making scenery for my 4 tanks, so they can fell at home and play around! Ho works fine, as 1/76... but i found that digi's looks quite small near 1/72 armor, but 1/72 soldiers and dioramas are fine! I should try to crash a 1/72 plane to see if it fits!!!