I cook my ribs for 4 hours unfoiled on my egg at 275. At 225-250 it would be longer. I would consider foiling the ribs when the bark looks solid. Tightly seal in foil after a sprinkling of brown sugar and a drizzle of peach nectar. They are done when a toothpick easily penetrates the meat between the bones. Then, let them rest uncovered for 15 minutes or so, then slice. That's what I do!!
Large Big Green Egg, Cold smokehouse,
UDS with hinged lid, Santa Maria pit
26.75" Weber OTG, Weber Performer, WGA
MAK One Star Pellet Grill, Smokey Joe Gold, Jumbo Joe Gold, Hasty Bake Gourmet
Custom wooden handles for BBQ's made by Marty Leach (oh, that's me)