It's easy and simple - just few points:
1. Stock rim
2. Replace (repaint) texture (here I had to make new material)
3. So, it will look like that:
That's just some kind of editing textures. I have made it with Photosnap Editor... For me six textures per rim is enought.
Colors: Light, Gold, Lime, Cyan, Red, Dark
PS: By that way, all rims will have different color options (except specials like O.Z. GTR, or 5Zigen FNO1RC with Chromed Lip - cause it's bronze from stock.