Tyranitar isn't uber because of it's type: Dark/Rock. There's alot of water and fighting type moves, so Tyranitar is easily KO'ed.
eg. Tyranitar vs. Infernape, since the latter is faster it is likely Tyranitar will be KO'ed with Close Combat.
Also, if Tyranitar should be uber, then you might as well say the same with Blissey, Weavile, etc. etc. etc.