1.In a small bowl, mix together salt, chili powder, black pepper, brown sugar, coffee, onion powder, and garlic powder.
2.Place the roast on small sheet pan. If the roast has a fat cap on it, score the fat diagonally about an inch apart with a sharp chef’s knife. Turn it 90 degrees and score again to form a diamond pattern. Season the meat all over with the rub, pressing it into the roast. Place the roast inside the fridge to marinate overnight.
3.When ready to smoke, take roast out of the fridge first. Open the vent of the smoker. Add water halfway up in the water bowl at the bottom of the smoker. Place the wood chips in the side tray. Place the drip pan on the bottom rack. Thread the digital thermometer through the vent. Preheat the smoker to 225°F for 45 minutes.
4.Place the tri-tip, fat side up, on the middle rack of the smoker. Place the digital thermometer in the fatter end of the roast, close the door. Smoke for approximately 2 hours for medium rare. The internal temperature should read 130 to 135°F. Be sure to check the wood chips and water at 60 minutes. Add more if necessary.
5.Remove the roast to a clean cutting board and tent loosely with foil for 20 minutes to allow the juices to be reabsorbed. Slice thinly against the grain.