Rear wheels own at bottom.

A buddy of mine has an '05 Grand Prix GXP and was asking me about his rear wheel alignment. He said he's already replaced his rear tires because they wore out on the inside. A year later, his new tires are looking worn on the inside. He said it looks like the bottoms of his wheels are kind of sticking out and was wondering if that is an alignment issue, or are the springs tired? He was seeking advice about where to take it. Any thoughts?

Have him take the car to an alignment shop and have it checked. It is possible that the alignment is out so far that it is causing the wear issues. There is also a possiblility that there are worn components. The alignment shop will be able to tell him what is wrong. A 4 wheel alignment costs less than a set of tires usually around $100.

How many does he have? I should hope the high quality Bilstein struts and springs have not worn out but you never know. The outward camber look is normal on the rear wheels. Is he running the stock P225 50 R18 wheel/tire size?

The tires he has on it are: Goodyear Eagle F1 all season P225 50 R18
The mileage on the vehicle is: 64k

im not exactly sure what part of the tire you're talking about, but if its what im thinking of, it sounds like the tires have too much air in them

One of the main reason why GXP owners see abnormal tire wear whether on the front or rear is because of the way the GM engineers designed it to help traction and compensate for torque steer. With the P255 45 R18 on front and P225 50 R18 on the rear you cannot rotate the tires like other cars to compensate for wear. Most owners will be lucky to get 20K miles on any brand tire installed.

Unless it has already been done then it probably would not hurt to get the alignment checked and then go from there. Check specifically for the proper camber settings and rear toe in.

im not exactly sure what part of the tire you're talking about, but if its what im thinking of, it sounds like the tires have too much air in them
What I was trying to explain is that the tread on the back two tires is worn on the side of the tire that is hidden, or closest to the tire on the other side, not the inner part of the tread on each tire. The owner believes it is due to the squatting appearance of the rear of his car. I am keeping him informed about what you guys recommend. I will let you know what he finds.

Thanks.