If your thinking of using metal flakes to put on your wheels it goes in the lacquer but on silver i suppose the only colour that would look good is silver tbh. Will make it super metalic.
I have done quite alot of metal flaking on things and usually have a dark base coat then apply a light colour metal flake, ie black basecoat with rainbow metal flake or blue basecoat with silver metal flake etc.
I have seen many colours with the same colour metal flake and it can be seen well and really makes it appear really metallicy and bright.