Hope this isn't too dumb of a question, but while looking for rotors on ebay I also noticed that companies were selling disc brake rotor shims or hub correction shims. Will I need these with aftermarket rotors and if that is the case, is it better to just purchase the OEM rotors to begin with. Just didn't notice anything in the factory manual about disc brake rotor shims. Any help would be great, just want to make sure I have all the parts I need on hand before I start. Thanks.