Unfortunately your Tyranitar calculation is a little off because the most likely set that Tyranitar will be running will be Assault Vest one, meaning Klefki can only barely manage a 5HKO at +2:
+2 0 SpA (custom) (Move 1) vs. +1 252 HP / 252+ SpD Tyranitar: 86-104 (21.28 - 25.74%) -- possible 5HKO
Calm Mind Klefki may be viable in its own right, but Tyranitar is not a Pokemon you want to use as fodder for setting up, which is unfortunate, as Klefki has a reasonably good match-up against most Tyranitar variants thanks to his Fairy-Type STAB.
That said, where is Klefki going to find the time to go +2? Gliscor, Landorus, Tyranitar, Hippowdon, and the like all force Klefki out with Earthquake (and 3 of those guys have STAB on it). In addition to that, Draining Kiss is but a 50 base power move, and Klefki only has an 80 base Special Attack Stat; all of his EVs want to go into HP and Defenses and you want to find Pokemon that are going to sit there while you Calm Mind up a few times. I feel as though more calculations are needed before Calm Mind Klefki should be seen as anything other than an inferior support set.
I did run across something interesting the other day:
Klefki @ Air Balloon
252 HP/ 252 DEF/ 4 SpD
Impish Nature
- Spikes
- Recycle
- Foul Play
- Thunder Wave
Air Balloon mitigates one of Klefki's only two weaknesses: Ground-Type attacks. By recycling Balloons Klefki can Spike in the face of Pokemon that would normally threaten it, such as Gliscor and Landorus-Therian, specifically Gliscor, who do not always carry a secondary attack in addition to their STAB Earthquake, forcing them out. While Landorus-Therian users may catch on quickly and keep spamming Hidden Power [Ice] or Stone Edge in an effort to force you to switch, you should, in most scenarios, be able to drop 2 layers of Spikes before being forced out. Like most Klefki sets, this one really appreciates Wish passing support from Pokemon like Vaporeon, or hazard removal from Pokemon like Lati@s, who are fast and force many Pokemon out.