Group 2: for children weighing 15 - 25 kgs (33 - 55 lbs), roughly 4 to 6 years. Booster seats that only fit into Group 2 are less common. Most are group 2 and 3, or groups 1, 2 and 3. Groups 2 & 3: for children weighing 15 - 36 kg (33 - 79 lbs), roughly 4 to 11 years.
Broil the ribs for about 5 minutes, until the sugar in the dry rub is bubbling and the ribs are evenly browned. Bake the ribs: Set the oven to 300Â°F. Move the ribs to an oven rack in the middle of the oven. Roast for 2 1/2 to 3 hours for spare ribs or 1 1/2 to 2 hours for baby back ribs. Halfway through cooking, cover the ribs with aluminum foil to protect them from drying out.
The lower the meatâs temperature, the less moisture it loses, but the longer its connective tissue takes to dissolve, too. You can get very juicy ribs by cooking them at 135 degrees, but making them tender takes two or three days. At 160 degrees, you get tender ribs in 10 to 12 hours. At 170 to 180 degrees, the meat is noticeably dryer, but the cooking time is a more manageable 6 to 8 hours.