Bottoming out? Scraping?
 

I have a 2009 G8 GT with 20" camaro wheels. The rear tires are 275/30ZR20s. I am having a problem with the car bottoming out on the highway when I have passengers in the back seat. At first I thought the rear tires were hitting the fender lip, but that is not the case. I'm wondering if anyone else is having this issue? Basically, my car is now a two seater. Has there been issues with the rear springs/struts??

The GXP struts and shocks are a well known upgrade over the v6 and gt ones.

For the tire size info, just double check ls1gto (only this one time :)) to make sure your setup is ok.