Tyranitar... which IV is your goal?

I have only one larvitar, hatched and came with only 23 candies. He is 97%.

I hatched two larvitars up until now and the stronger one has 89% IV. Normally I set my minimum at 76%, but ideally and especially for despotar where candy is so rare it would be > 87% for me. With Dragonite I set the minimum at 84%.

My bar is 82% for every pokémon.
The only exception is Blissey that I'll consider leveling anything with good DEF and ATK.

Most of us, especially if you haven't seen one yet, are only getting then from hatches. So, I'd say the minimum is 67% for the absolute worst hatch. Regardless, he's primarily an attacker, so IV (and therefore CP) are less vital.

When it comes to Tyranitar, I think more in a defender than an attacker, so for placing in a gym anything with high CP is good. Also in my own experience, what really matters in the cp calculations are attack and defense, hp is not important at all, it can be a 15/15/0 ivs and steel a good pokemon, so I would say for a tyranitar anything with 15/15 attack defense or close.

For rares I look for greater than 90 for defender and 70 for attacker