Sorry I'm late to the party on this one, Brad - not sure how I missed it!
I treat tri-tips like a beef roast or prime rib: low and slow at 200-210 box temp, until the middle hits 128 internal, then reverse-sear in a hot oven or on the grill. With this method, you get your med-rare pink all the way to the edges - no overcooked outer edge!
Tri-tips get a rub with Jim Baldridge's Secret Seasoning (best-ever rub for beef), and are ONLY smoked with oak - "Santa Maria" style!
The pic is a couple getting a sear...sorry I didn't get a sliced shot of these; pretty sure we were way too busy devouring them like we skipped lunch!