Alignment issues on last-gen W body vehicle ('08 LaCrosse)

[GM-midsize-guy]

One thing I have noticed since my car was new, over 7 years ago, is that the rear tires bowed out a little bit. You could see this when approaching the car from the rear.

 

I was told it was normal, by both the dealer and by tire stores. I never studied Grand Prixs or Monte Carlos of the same year to see if the tires did that. That seemed to be the case on some LaCrosses.

 

The tires wore well for the first 30,000 miles and I'm sure I knocked out the alignment somewhere along the way. They are wearing faster now. I will need to replace them and get an alignment at the same time. I sure didn't get the 60,000 miles advertised for this OEM tire. My last W-body's original tires went 80,000 miles.

 

Question: Is this bowing out of the rear tires normal for some W-body makes? Is this the sort of situation where shims will need to be added when I get a 4 wheel alignment? I've never seem them insert shims during a wheel alignment on any car I've owned.

 

"Bonus" question: If you were going to go into some high quality Michelin tires, would you also replace the struts or do that a little later? I've heard OEM struts typically last 50,000 to 60,000 miles, on average.

 

Your input is highly appreciated. Thanks!