Tiger are too slow and will be raped by stickies, out-ranged by fireflies.
Not good enough to fight a Pershing, which has a 90mm gun.
Bigger than the Tiger's 88.
Pershing: sloped armor.
Tiger: flat armor.
Your Tiger is faster than a Rifleman squad, if you get stickied it's your own fault. The Firefly out ranges you, but it is a dedicated AT piece designed to take out heavy armour, the Tiger is a heavy tank dedicated to Heavy AI and good AT WHEN it's in range.
The Tiger kicks the shit out of the Pershing. The Tiger has a bit more health, much better armour and penetrates the Pershing more often than the Pershing penetrates the Tiger. If you don't believe me, I suggest looking into the statistics - Which is something you should do before making any balance claims.
Size of guns or angle of armour is irrelevant, CoH does not and will not work on realism. The game does not have an engine that would suitably support such a game style, therefore it works on pseudo-realism.
After all, if we wanted realism, we'd see about 20 or so Shermans for every Tiger in field.