i recently got a set of 18 inch aftermarket rims and Kumho tires for my 2002 c240. The tire shop bored the centre out a little to make them fit better and added a plastic shim around the centre hub to make it tight against the rotor. When i'm driving 130+ km (highway), sometimes i experience a very noticeable vibration that even my seat shakes. is this normal when stepping up to 18 inch aftermarket rims (expected). If not, will alignment help? any suggestions please.