Place 3 fist-sized chunks of wood in a smoker and heat to 250 degrees F (121 degrees C). While the wood burns down, mix salt, pepper, garlic powder, onion powder, chili powder, and cumin together. Apply the rub to both sides of the ribs. Add ribs to the smoker, bone-side down, once a thin blue smoke appears. Smoke for 2 hours. Wrap ribs lightly in aluminum foil to retain juices. Continue smoking for 1 1/2 hours at 225 to 250 degrees F (107 to 121 degrees C). Remove foil and continue to smoke until meat is tender but still stays on the bone, about 1 hour more, brushing lightly with barbeque sauce in the last 15 minutes. An instant-read thermometer inserted into the center should read 145 degrees F (63 degrees C).