Been thinking about this one a lot. Read all the responses. Lets assume the membrane was removed. With ribs you basically get tough, tender, fall-off-the-bone tender, or dry. "Tough" ribs to me mean they may be cooked but have not been cooked long enough at the desired temperature to get tender. On the other end of the spectrum is dry. If they were dry they typically still fall off the bone, just WAY overcooked. Trust me, over the decades I've ended up with them all before I found what works for me every time.
I don't wrap my ribs any longer in my smoker, cooking ribs in the 225-235 range for roughly 5.5 to 6.5 hours for spares, at least 4 hours for BBs, using the 1/4" to 1/2" draw up on the bone as a visual check for doneness. I've found BBs to be more temperamental and only smoke them when requested. For the finished product I personally like 1/4" draw with a little tug on the bite. My wife and kids like a 1/2" to 3/4" draw and fall off the bone. I've had BBs take as long as spares to finish, but they are generally done in 2/3 to 3/4 the amount of time. I only open my smoker 2-3 times during the entire smoke to spritz, then one final time to sauce. I keep as much heat in the smoker as I can even when spritzing. If you are opening more than that, I suspect your temp recovery time is impacting your final result.
Decatur, GA is only at 1043 feet elevation. That's only about a 2.5F difference in boiling point of water (water boils at a lower temp the higher you go above sea level). Use 230 for a bit of a margin, 235F if you are higher up in the hills.