You need to test them for tender by sticking a probe or skewer in the meat between two middle bones. If the item goes in with little to no resistance, the ribs are done. No particular temp. Did you foil at all? If not, and if you cooked low/slow in the 225-250 range they were probably not cooked long enough.
Just for reference, because I'm no guru, yesterday I smoked baby backs at 275 for about 2.25 hours, then foiled with just a tad of apple juice for about 20 minutes. They were the best I've ever done. I just throw this out there. You might try it once to see if you like them. Do test for tender before you pull them