In a small bowl, mix together the brown sugar, paprika, garlic powder, onion powder, salt, and black pepper to create a dry rub.
Rub the dry rub all over the racks of ribs, covering them evenly.
Place the ribs on the grill and cook for 1 hour, turning them every 15 minutes.
After the ribs have cooked for an hour, brush them with barbecue sauce and continue to cook for an additional 30 minutes, basting with more sauce every 10 minutes.
Once the ribs are tender and caramelized, remove them from the grill and let them rest for 10 minutes before serving.