This is probably the best sprite you got in your gallery, very nice job! The head could have some work though, and the upper part of the body. Also, the left arm (for Tyranitar the right) is too light, and the outline is too dark.
Of course, these are just minor things and you don't have to chance them at all. Great job, once again
The head is a bit too big, if you look at the Tyranitar sprites from GameFreak, you see that the mouth/nose area is a bit 'sharper'.
About the upper body, it's very skinny compared to the lower part. See the upper part as a kind of 'extra armour', so it should be wider or at least the same as the chest area. The neck should be wider too.
I hope you understand what I'm talking about, because I'm not English. And once again, your choice to change
The skinniness was actually intended, that's how the person requested it because they didn't like fat Tyrannitars xD That's probably why the head looks bigger in comparion too, I think. Thanks for the advice though!