LM300HTD

I am having an issue with my 2012 C300's front wheels and tires wearing out due to rubbing on the inside. Has anyone heard of this? I think the dealership isn't being completely honest here. They claim that the Continental Tires that were included on the upgraded AMG wheels are rolling too much during cornering and causing the wheel and tire to wear. They are only offering to replace the 2 front rims but say I have to buy 4 new tires as I am past the accepted mm wear for them to also replace my tires. This sucks as my tires still have at least a good 15 or 20K left on them. Any suggestions???