Heat the smoker to 250 F.
If necessary, remove the membrane from the back of the rib racks, and pat the ribs dry with a paper towel.
Liberally sprinkle the seasoning rub on both sides of the ribs and work it into the meat with your hands until they are completely covered.
Place a foil pan on the grate of the smoker and fill ½ way with water. The water will keep the smoker hydrated and the meat juicy.
Place the ribs on the grate of the smoker, meaty side up, and cook for two hours, spraying with apple cider vinegar at the top of each hour.
Remove the ribs from the smoker and slather them liberally with barbecue sauce on both sides.
Wrap the ribs in a double layer of heavy foil and cook them for another two hours.
After two hours, remove the ribs from the smoker, unwrap them, brush on some more barbecue sauce and cook them for one more hour, or until the internal temperature reaches 195-205 F.
Transfer the ribs to a platter and allow them to rest for 5-10 minutes before serving.