Hardwood chips or chunks of whole pecan wood should be used.
Prepare the grill for indirect heat: If you don’t have a smoker with an offset box, you can build a fire on one side of your grill and then put a piece of foil on the opposite side of the grill. This will create indirect heat.
Prepare the ribs: Remove the thin, papery membrane skin from the back of each rack of ribs by pulling it off in a sheet with your fingers, using the corner of a kitchen towel to gain a secure grip, or with pliers.
Prepare the rub: In a bowl, whisk together chile powder, salt, pepper, cumin, rosemary, thyme, garlic powder, and sugar.
Generously season ribs with the mixture, rubbing onto both sides of the rack.
Place the ribs, bone-side down, on foil to cook with lid closed. Cover the grill and keep the temperature of the grill at a constant 225-degrees. Cook the ribs for about 3 to 4 hours or until tender.