I'm no expert, just picked up the basics over the years. Truthfully it isn't all that hard, just have to be patient as you carefully outline the part of the picture you wish to manipulate, then just mess with a few settings to change colors etc.
I certainly don't mind doing it for people. If anyone wants to do the "leg work" and first find me the pictures (one of the car and one of the wheel) that look like they're taken from a similar angle, that makes my job easier. If you want something photoshopped just PM me with the pictures.
I know I still owe BandAid a white vector wheel picture.