Rear tire wear

Hello Gents and Ladies,
I'm new to the Forum.  I have a 2002 CL500 and noticed both my rear tires are worn the same amount on the inside.  There's a lot of tread left on the outside of  these tires.  The tires have only 13000 miles on them, and I had all wheels balanced and aligned to specs when I bought the tires.  Is this normal for the rear wheels on the CL?  Anyone know if it would affect the handling if I had the alignment shop adjust  the specs to give even wear on the rear tires.  I'm buying new tires and don't want them ruined this way again.
Thanks for your attention!

You have negative camber and that's causing the inner tire to wear out faster.
The solution is camber kit.
Please check http://www.mercedesforum.com/m_78627/tm.htm