question about the rear end

hi im new to subarus in general so bear with me i've been looking for a wrx for quite some time now and have recently found a 2002 wrx with 40,000 miles and ebiach springs for 14,000. I however noticed that the right rear tire is chamberd out about a half inch, i can also tell that this buy the way the tire tread is worn. i was wondering if this is a severe problem or a minor one and your opinions about whatever.
thanks

It's a severe problem, it sounds like one of the linkage arms is bent, especially if it's only one side.