Well, historically the Tiger was a very tough opponent.
I know the T-34 we have is just about completely impotent against it. As far as the Panzer IVH vs the Tiger... the Tiger should be vulnerable frontally from <500 meters. To the side from <1000 meters, from the rear also <1000 meters.
The Tiger would pop the Panzer IV like a grape from within 2000m+ if it hit the turret (which only has 50mm of armor on the front), and probably merely kill it from ~2000 yards with a hit to the front hull.
I don't really have a problem with the Panzer IV vs Tiger matchup, a smart Panzer driver with good aim would probably be able to work himself into a position to kill the Tiger.
The T-34 vs Tiger matchup on the other hand, I find completely imbalanced, and I think we really should have 3 or 4 tungsten rounds in the T-34 just because the T-34 literally cannot kill a Tiger 1v1 (at all, from any range or angle) unless the Tiger driver is mentally retarded, AFK, or both. It take 3 hits to the same "panel" (either left front, right front, left, right, or rear) on the turret at exactly 90 degrees incidence (if you are even a smidge off, all the rounds will ricochet) to disable the turret. After the turret is disabled it takes a seemingly random (but high) number of shots to actually kill the Tiger (to the side or rear, same rules for hitting as for the turret). In my tests, this number was between 8 and 12 additional hits.
Now, our T-34 takes ~12-13 seconds to reload. So, even assuming you manage to get yourself into a perfect spot at 5 yards on an unsuspecting Tiger... it would take you ~40 seconds to kill him. The Tigers turret takes a full minute to spin 360 degrees (well, IRL anyway, no idea in game, I've never timed it). The requirement for 3 hits on the exact same panel of the turret means you will never have time to disable the turret on a Tiger before he brings it around to kill you, no matter where you are relative to the turret when you start shooting.