Suspension Noise problems of the 2007 Chevrolet Impala

Bought 2007 Impala new. Have replaced rear tires 6 times due to camber issue. Impala is designed with no adjustment for camber on the rear suspension. Tires wear on the inside at a fast rate. Nothing in the trunk to cause weight issues, standard highway driving on a daily basis. Tire sound is horrible and increases with speed. First set of tires replaced at 9,000 miles. Gm recalled police models of the Impala to fix the issue, but not Impalas that weren't police models. So gm knows there is an issue with the rear suspension causing excessive tire wear but won't perform a recall. My wife wouldn't even drive the car because she was afraid tires would blow out on the highway. 6 sets of tires on a vehicle with 90,000 miles is obsurd. I finally had to have another shop install aftermarket camber adjusting bolts and get an alignment to fix the issue. Shop I dealt with says they've been performing this repair on Impala's since mid 2007. $20 for the bolt kit and $80 for the alignment. $100 to fix an issue (not including tire replacement costs) and gm won't own up to it. This is a basic design flaw that gm has been aware of, with no action being taken on there part.