At least a half hour and up to 4 hours before you plan to cook the ribs, peel the membrane off the back of the ribs and trim any excessive fat. Season the ribs liberally on both sides with the Rib Rub. Refrigerate.
Prepare the grill for cooking over indirect heat at 300 degrees F using apple or cherry wood for flavor. Place the ribs directly on the cooking grate, meaty-side up. Cook for 1 hour. Flip and cook another 30 minutes. Flip again and cook until they are nicely caramelized and golden brown, about another 30 minutes, but may vary depending on your grill. Transfer the ribs to a platter.
Lay out two big double-layered sheets of heavy-duty aluminum foil, each big enough to wrap a whole slab of the ribs. Transfer the ribs to the foil, meaty-side up. Fold the foil up around the ribs into a packet. Seal the packets snugly, being careful not to puncture the foil with the rib bones. Return to the grill for 45 minutes to 1 hour to reach your desired degree of tenderness. The best way to determine the doneness is to open the foil after 45 minutes and feel the texture of the meat. It should be very tender. Transfer the foil packets to a platter. Raise the temp of the grill to 400 degrees F. Remove the ribs from the foil and return to the cooking grate. Sprinkle lightly with additional Rib Rub #99. Cook for 5 minutes. Flip and sprinkle the other side lightly with the Rib Rub and cook for 5 minutes. Flip one last time and cook for 5 minutes more. Remove the ribs to a platter. Serve 1/2 slab to each guest.
Combine all ingredients, mix well, and store in an airtight container.
Excerpted with permission from Ribs, Chops, Steaks, & Wings by Ray Lampe (Chronicle Books, 2010)