I'm having similar issues. Premature inside rear tire feathering, tire out of round, humming noise from rear when driven on highways. Rear wheel bearings were just replaced a couple weeks ago. My mechanic feels the rear strut assembly is not at fault and they are good. Drives arrow straight.
I took it for an alignment yesterday, they took one look at the rear tire wear & r fused to do it stating the rear strut assembly was at fault. Quoted me $300 Canadian per side for parts alone! I live near Detroit & know I can get Monroe complete struts for $157.99 per side @ O'Reilly's.
What do you all think? Do I go against my trusted mechanic who says put another set of tires on it, then get an alignment, or trust the alignment shop who says replace the rear struts and get the alignment? I know my Nokian tires are shot on the rear, but my mechanic says they'll be fine for quite some time as my winter set. Get new tires for my Chrome rims and then get the alignment. If the tires start wearing, which he doesn't think they will, then get complete struts. I think I can see the top of the rear tires tilting in at the top myself. not sure if that is excessive camber or castor or toe? I could google it & find the terminology I guess.

 

I like how people run away like cowards at the sight of strut tower rust.

Lol, mine is way worse than any pictures shown in this thread. I've already got a plan to tackle it. It won't be a "proper" fix, but a fix that will make the car last at least another 5 years.