Ok so here's my dilemma after a couple 100 miles. I put nitto 555r 305's on the back, waited until break-in period and took my car up to 120mph. But I'm getting vibration starting at 117 mph and up consistent! Had the balance check and redone and still same issue. also checked the front. I guess I'm going to have to put the Pirellis back on and see if its still there, and go from there. What a pain!