Originally Posted by A Y
I agree with dah328. The differences are small enough that it's hard to tell from the pic if there's anything wrong, especially with the tires at such low tread depth. I'd put a new pair of tires on it and watch how they wear. Here's an alternate explanation: you mention that the right rear kept slipping when you got on the gas hard, which means it's pretty easy to slip the tires.
The tires could have been wearing evenly until recently, and then due to road conditions or loading on the suspension, the right one might have slipped a bit more. This caused more wear on that tire, and the tire became easier to slip, which caused it to wear more, etc. in a positive feedback loop.
I kind of agree, there is very little difference judging by the photos, maybe irl its more pronounced. The way it was described one tire is bald and the other is brand new.
Per sgoomba's post, good catch, it could be the diff, but unlikely, check the BMW forums and see if its a common problem. I'm back where I started, I think you have an element of the suspension that's off, if in fact anything is wrong. Those photos don't give me the feeling that there is definitely something wrong. In general, I think you should take this question to a BMW forum. Not trying to be a dick considering my recent postings, I'm serious, i use an Audi forum and get tons of detailed information that I would never get here.
Not sure who said it but I kind of disagree on rears wearing faster, the fronts take the turning and braking load. I have not had a true rwd car for a long long time but it seems illogical unless you're spinning wheels a lot. I base this on nothing.