Help with ev training Tyranitar?

Well it would also depend on your moves. My Tyranitar is a "cursing" Tyranitar, so I trained him on attack and HP. Basically Hit Points count as both of your defences, cause bulky pokemon (sometimes) don't have too much health. If you have a Normal Tyranitar then I would split them between his Sp Defence and Health. He has enough Defence, so you don't really have to worry about that. His Sp Defence isn't all that great so, I would increase that and Health just to make him take more hits.