2011 750lix rear tire wear

I was told by the dealer that I need to replace the right rear runflat due to tread wear as,
it wears uneven compared to the other tires. Is this accurate?

I purchased the car in 9/2012 with 29,000 miles from a Mercedes dealer. It now has 36,000miles. The right rear tire definately has much more wear than the other 3 which have fairly even tread wear.

Also, can and should I be rotating the rear tires (275)? Thank you.