I bought a 2008 G35x with factory 18" sport rims, the car has 65k on it, dealership say;s they did a 4 wheel alignment before purchase but the car wonders all over on uneven roads and the back tires kind of hop to the right after hiiting a sharp bump or ridge in the road, I have takening the car back them twice and they tell me everthing normal, anyone have any similar problems or should I not go back to infiniti for service and go somewhere else??