uneven tread wear is an indication that your wheels need aligning. With time, your wheels will be a little off-center, causing them to tilt vertically at a certain angle that results in uneven tread wear. I know this is true for the front wheels, I'm pretty sure it's the same story for the rears unless someone here can clarify this further
its pretty common actually. Especially if you have wider tires. Mine do that as well and I'm running 245/50/16s. Rotate your tires regularly (unless they are different sizes front and back). I hear adjustable camber plates work nicely. I'm thinking about getting some myself.
there are a couple different things that may cause this
-bad ball joints
-and the most common one and most likely the case if you need caster camber plates
is the car lowered at all? if your doing caster camber plates you might as well do the struts and check your ball joints to see if they are all good because they are all playing a role in your front end alignment, and having one of those bad and getting it aligned isnt really doing you any good
yea all you can do is check the wheel bearings. its a solid axle so there is no adjustment for anything. until you start getting into adj lca which allow you to position the rear end differently. if you are running some crazy wheel spacers or odd backspace on your wheels and they flex a lot then you may encounter this problem, but that is a long shot.