Tri tip is a steak-like cut with very little connective tissue, and that means it should be cooked to the same doneness as a steak would be: 130°–135°F (54–57°C) for medium-rare or 135°–145°F (57–63°C) for medium.
The temperature to cook the tri tip at is kind of up to you. We prefer cooking it slowly at 220°F (104°C) and then reverse searing it on a hot grill. But higher temp cooking methods will also work.
For more on tri tip , see our post on smoking tri tip with a reverse sear.