Irregular and premature tire wear can be caused by the lower control arm bushings cracking, resulting excessive movement at the control arm pivot point. Ball joints can also wear out prematurely, causing similar tire wear symptoms. I some cases it may be necessary to replace the lower control arm, including bushings & ball joint to correct this concern.Google+
Car Problem Reports
Mercedes-Benz CLK430 Premature Tire Wear Due to Cracked Lower Control Arm Bushings
Mercedes-Benz CLK430 Problem
Visitor, 2002 Mercedes-Benz CLK430, 60,000 mi
For some reason, I have to replace the front lower control arm bushings about every year as they crack/break and these are dealer parts.Not sure about the quality of CLK's these days.