2 cups hickory chips, soaked in water to cover for 30 minutes and drained
Place the ribs on baking sheets. Combine the brown sugar, paprika, salt, garlic powder and black pepper in a bowl. Sprinkle 2/3 of the rub over the ribs and rub it into the meat with your fingertips. Refrigerate the ribs.
Set up the grill for indirect grilling and preheat to medium. If using a charcoal grill, place a drip pan in the center under the grate. Toss the wood chips on the coals. Cover the grill and adjust the vents to obtain a temperature of 325°. If using a gas grill, set it up for indirect grilling and place the wood chips in the smoker box (if your grill has one) or in a foil smoker pouch.
Pour the orange juice into a spray bottle or mister. Spray the ribs on both sides with orange juice and set them on the grill grate away from the fire. (A rib rack will help you fit 4 racks on a small grill.) Grill the ribs until cooked, 1 1/4 to 1 1/2 hours. Spray them with orange juice every 20 minutes. Five minutes before the ribs are done, lightly brush them with the Citrus Barbecue Sauce. (Save most of the sauce for serving.) When ribs are cooked, the meat will have shrunk back from the bones and will be tender enough to pull apart with your fingers.
Transfer the ribs to a platter. Sprinkle the ribs with the remaining rub and lightly brush again with sauce. Serve the remaining sauce on the side.