Mix seasoning salt, garlic powder, and black pepper together. Rub onto ribs (store excess rub in an airtight container). Place rack of ribs, rib side down, onto grill. Cook for 15 minutes. Turn ribs over and cook for another 15 minutes. Remove ribs from the grill just before they are cooked to your liking. Empty BBQ sauce into a roasting pan. Transfer ribs to pan with heated sauce, cover, and let the ribs continue to cook for another
10 to 15 minutes. Serve with sauce on the side.