Problem was that due to the German war situation at that time they were rarely well maintained or not asked to do overly strenuous things. Based on the Soviet testing, they weren't well made either. The Soviets found the armor to be improperly tempered rendering it much weaker than it ought to have been.
Due to slave labor perhaps? Dont know Im just throwing it out there. Its not like the forced labor never intentionally did anything like that.
I may be wrong but its pretty much my understanding not that they were unreliable. but that they were so complicated they were impossible for the crew to repair in the field when they broke down. Kinda like todays cars. You average owner cant to much of the repairs themselves anymore without being a tech.
combine that with by the time the tiger arrived the Germans were strained and largly either on the defensive, about to be or under heavy combat.
The single largest problem with the king tiger that I am aware of was its sheer size and weight which limited its movement to specific bridges and terrain hardness. After a heavy rain it sucked from a manuverability standpoint and would easily get bogged down if the ground wasnt firm enough.
Unfortunately we dont as of yet have varied terrain hardness or difficulty other then grade. So terrain should never be an issue in AH.
It size was an issue particularly in towns where the roads were often very narrow.
