Ever experienced problems with wheel balance giving you vibrations through the steering wheel? Ever had someone tell you just to change the steering dampener and it will be OK? How does that dampener get worn out? It happens by just doing it's job! Dampening vibrations from (usually) the wheel/tire assembly. I have worked on a fair number of cats and find so often that the tires/wheels have been fitted just like you would for any old car. Prestige vehicles are a whole lot more sensitive and manufactured to much tighter tolerences than many give them credit for. It is for this reason that tire sellection and expert fitment are paramount to having your cat or any prestige vehicle drive smooth and quitely. I'm a newby to this board, but I can't help but wonder how many people have had the same frustrations as you had experienced. Let me know if you'd like some more information.