So I get home from work today to have my sister immediately rush up to me and start asking to look at her car. She tells me that there is something going on with her steering and that she can smell rubber burning. So I go ahead walk out to the car and get in and start it, but then I think to myself to do a quick walk around and look at the wheels. I come around to the driver rear wheel to see it pointing in and rubbing on the trailing arm, so first thought for me is to check out the lug nuts (wouldn't be the first time a lug stud has broken off). So I pop the cap off and everything is sitting snug against the hub, so under the car I go! Get underneath and the "control arms?" appear to be fine and have no play, the strut also appears to be fine. Anywho on to the questions...

Is it possible that the hub has split and is on the verge of falling apart? (She says it started doing it just blocks from the house)

Could it be the knuckle itself is defective?

What else could it be?