I run 255/25/45 michellin pilot super sports and ever since I installed my new 27mm rear sway bar I can see that my tires are rolling over on themselves around hard corners especially on the track. My nitto invos never did that. I even tried putting 50psi in the rear tires and still j have the problem. What am I missing here??

 

Well, your suspension is now doing less of the work handling your car's weight transfer. It's decently normal as long as it doesn't pop the bead.

27mm rear IS VERY aggressive that being said.