Gene, I agree with Ed. Sounds like you needed a little more time. I usually go about 5:15 @ 235, but it's taken close to 6:00 at times. Depends on the ribs - some cook faster than others. It's all about feel, for me. I start checking around 5 hours, with a wooden toothpick. If it goes in tender, and I can pull the meat sideways (away from the bone) without breaking the toothpick, they're done! If not, I go another 20-30 min and check again. No "cookie cutter" recipe, just a starting guideline. The meat will tell you when it's done!
Chris - I doubt you'll ever get tender ribs using 225 for 4.5 hours. Increase your temp to 235, and go longer. Also, putting the rub on the night before, and resting (wrapped in plastic) in the fridge is the preferred method. It allows the rub to penetrate the meat, and the salt in the rub acts as a "dry brine," which will help the meat retain moisture. I think your issue is time and temp, not when you applied the rub.