Prepare the ribs by scoring the membrane on bone side twice along the length. Rub 2/3 of the dry rub onto the three rib racks, most on the meat side. Lay HD foil to hang over by a couple of inches, on a half-sheet baking/cookie pan. Place the ribs, bone side down, in the pan and cover with more foil. Place in the fridge to cure for 4 hours min to overnight max.