Mix all the spice rub ingredients together.
Add spice rub to the meat.
Cover and refrigerate overnight, or 6 hours minimum.
For the Whiskey Chipotle BBQ Sauce:
Add whiskey, garlic, and onion to a large skillet.
Simmer for 5-6 minutes, or until onion is cooked and translucent.
Add black pepper, salt, ketchup, tomato paste, vinegar, liquid smoke, Worcestershire sauce, brown sugar, and chipotle powder.
Bring everything to a boil.
Simmer for 15 minutes.
For a smoother consistency, strain the sauce.
Heat the grill to 350 degrees F.
Place the meat on the grill.
Apply the first layer of BBQ sauce.
Close lid and cook for 10-20 minutes.
(For smaller tri tips, 10 minutes)
(For larger tri tips, 20 minutes)
Turn and apply another layer of BBQ sauce.
Close lid and again cook for 10-20 minutes.
Tri tip is ready when 145 degrees F for medium rare, 160 F for medium, and 175 F well done.
Cover with foil paper for a minimum of 10 minutes before slicing into thin slices.