After some research I have concluded that the Tiger's top armour is 25mm thick and an RPG-40 grenade can blast through 20mm of armour. However, by 1944/1945 the Germans were forced to make tanks with poorer quality of steel hence I felt it was appropriated for me to include this. Therefor I managed to blast through the top. I simpely had no other way to destroy the tank properly, either this or nothing as far as I know.

Edit: I took the initiative to lay out a logical battle plan for the Germans, as with what they are trying to preform. (Hiding their larger numbers and other tanks untill the Russians have advanced closely so they can suddenly come out of cover and blow them away.) Them judging that we have received poor information about their size and numbers. This however can be changed if the host does not agree.