Pat the ribs dry with paper towels, then lay them on a foil-lined baking sheet.
In a small bowl, stir together the salt, black pepper, brown sugar, garlic powder, onion powder, smoked paprika, cumin, and thyme. Coat the ribs on all sides with the dry rub, then arrange in a single layer. Let sit at room temperature for 30 minutes.
Preheat your oven to 250°F and place one rack in the bottom third position and the other rack in the top third position (about 6 inches away from the broiler).
Cover the pan tightly with foil, then place on the bottom rack and bake until an inserted digital thermometer reads 195°F and the ribs are fall-off-the-bone tender, about 2 hours to 2 hours 20 minutes.
Carefully remove the ribs from the oven (there will be liquid in the pan) and set the oven to broil. Uncover the ribs and carefully drain and discard the cooking juices. Liberally brush the BBQ sauce onto the ribs, turning to coat each rib completely.
Return the uncovered pan to the top rack and broil until the sauce thickens and the tops of the ribs begin to caramelize, about 5 minutes. Watch closely, so the sauce doesn’t burn.
Remove from the oven, place the ribs on a serving platter, and enjoy immediately.