About one hour before smoking, make the dry rub. Combine sugar, salt, white pepper, onion powder, cayenne pepper, lemon peel and apple pie spice in small bowl; mix well. Coat both sides of ribs with a little vegetable oil and sprinkle with lemon pepper rub. Set aside at room temperature for 1 hour.
Heat charcoal or gas grill for indirect cooking at 230 to 250 degrees F. Add drained wood chips, if using.
Place the ribs, meaty side down, over a drip pan and cook for 2 hours. If desired, spray both sides of ribs with apple juice. Add about 12 coals to a charcoal grill every 45 minutes or so to maintain the heat.
Remove ribs from grill. Double-wrap each rack in heavy-duty aluminum foil. Return wrapped ribs to the grill and cook for 1 1/2 to 2 hours more over indirect heat, until very tender. Add more coals as needed to maintain temperature for a charcoal grill.
