Stir together paprika, sugar, chili powder, salt, cayenne and black pepper in a small bowl. Line two 13 x 9 x 2-inch baking pans with foil.
Place ribs on racks in pans. Sprinkle spice mixture over ribs, patting to help mixture adhere. Turn ribs to coat all sides. Cover with aluminum foil; refrigerate for 5 hours or overnight.
Heat oven to 450 degrees F. Bake in same pans, uncovered, for 30 minutes. Remove from oven; carefully pour off liquid if needed.
Reduce oven temperature to 300 degrees F. Loosely tent pans with aluminum foil. Return to oven and bake for another 30 to 45 minutes or until fork-tender. Remove aluminum foil for the last 20 minutes of baking. Makes 10 servings.