You are correct, no way BB ribs are done in 90min at 225. Temp will usually only get you in the ballpark and can be completely wrong if the thermometer is placed wrong (too shallow, too far through, against bone...).
Cook them 3+ hours and start probing them every 20min until your probe goes through the meat "like butter." Keep notes on your cooks so you have a reference for future cooks and, once you find what works for you and your cooker to get the perfect result, you'll have something to reference/remind you when you cook that meat again. For example; referencing my FEC100 notebook, I know I'll need ~4 hours at 275 for St Louis cut ribs, uncovered, with a diluted apple spritz every ~20min the last hour to get them the way I and my family likes them (just a bit of pull to get the meat off the bone, not falling off). I probe when I spritz that last hour...
Plus, play around/experiment a bit. Based on recommendations here years ago, I tried cooking at 275 (instead of 225) and I found I get as good (or better) results in less time so, I go 275 on all my cooks now.