Combine the spices and garlic in a bowl with the garlic, salt and pepper and mix to combine. Coat the Prime Rib Roast Roast heavily and evenly and set aside until the coals are ready. Get coals ready for grilling and soak wood chips in water, wine or apple juice for smoking. When the coals are extremely hot, sear the roast over the hottest part of the grill evenly on all sides. Add the wood chips and move to the coolest part of the grill. In a flat smoker, this is farther from the firebox. In a column smoker, this is higher up from the coals. The ideal smoker heat and time is 300 degrees for two hours. If you don’t have a thermometer on your smoker, continue checking the coals and wood chips. Use a meat thermometer until your roast has an internal temperature of 130 degrees. Remove from the smoker and let rest thirty minutes before slicing.