[Hary Gahtoe]

You Forgot To Mention The Car Was Lowered

You need the correct term. Its rear camber. Thats what wears out the inside edge. The ONLY way you will ever stop inside wear is by using a K Mac adjustable bushing kit or adjustable control rods. A dealer won't touch you or lie and take your cash and do nothing. Factory MB rear suspension is NON adjustable. After you choose one anybody can reset your camber.
Bon shaunce Mon Ami

 

[Hary Gahtoe]

Its Gonna Cost $$$$

I'm Tired. I just caught the part one tire is wearing. Can't you feel that in steering feel? Thats huge chasis stress. Either you have accident related damage to only one side or your coil spring is comprimised. It might just be a missing spring pad. For your sake pray for coil springs. They run $250-350 H&R. You need to pull the wheel off and check it all out from one side to the other.

 

[Hary Gahtoe]

This`is Gonna Cost You New Springs @ Minumum

There's No way to correct camber in a "stock" W208 MB rear besides replacing your springs. Especially wearing out the inside edge of the tire.
The adjustment others above referred to is toe/thrust and its very small at best. Not camber. You're describing classic sacked out springs in stock ride height.
Don't forget to replace the spring pads.

 

[Hary Gahtoe]

Camber Bars Are For Lowered Cars Not Messed Up Stock

new bushings or new upper links are required to adjust rear camber.

rear links

View topic - Lensolo Adjustable Rear Camber Arms | THE Mercedes-Benz & AMG Forum for and by the Enthusiasts | MyMBonline.com

This car is Stock. This approach is wrong and dangerous with a messed up stock suspension. The suspension must be corrected without any adjustable aids. Remember this is causing exteme tire wear only on one side.
If this car was lowered it'd be prudent to use camber bars. I used adjustable camber bars on our lowered Cabriolet.
Replace the springs and spring pads. It should be obvious as hell.

 

[Hary Gahtoe]

Your stealorship is freakin blind and lied thru their teeth. Its physically impossible to wear out 1 inside rear tire alone and correct it with front toe.

Unless you stated rear wear and its really front tire that was wore out