Rib Question

I have a question on smoking ribs. I use dry rub and apply this at least 24 hours prior to smoking them. I have a Smoker with a offset firebox and use a varity of hard wood, I smoke them for about 4 hours. (I remove the membrane on the back as well prior to smoking), They always come out tasting great but I've never been able to get the meat to just fall off the bone. Am I missing a step in the process?

Let it cook longer. The connective tissue needs more time to breakdown.

Try to keep your temp at 225 - 250 for about 5 to 5 1/2 hours. Put a tray of water under the ribs close to the opening from the fire box. Put some cut up apples in the tray of water. About once an hour spray the ribs with water or apple juice, but do it fast so you don't lose your heat.

Use a mop and wait until the meat has drawn back from the bone. I Four hours wouldn't be long enough at that temp on my pit.

Thanks, I was wonderinf if I should be cooking them longer. I just worry about them coming out dry. I like the idea about the water pan. I use that all the time when I cook on my gas grill and I use aa varetiy of juices instead of water.
Thanks again.

To each his/her own, but for my money "falling ofdf the bone" ribs are overcooked. They should come off the bone easily, but retain their texture.