Had a similar thing happen to two of my Santiago's... Didn't detect any vibration whilst driving but I did notice that I was constantly losing tyre pressure on both rear wheels.
At first I thought it was down to a slow puncture, but when I took the wheels off to inspect further I noticed both had buckled.
I can remember running over a couple of "shallow" potholes at some point that could have contributed to them buckling, but at the time I thought nothing of it.
I've had numerous other 19" (& 20") alloys on other vehicles over the years but I've never had this problem before. Maybe I was just unlucky in this instance?