Well, I finally stuck the badges to the center caps. I decided leave the center caps unpainted, and I used a combination of adhesive and double sided emblem tape to hold them on. I used 3M's double sided emblem tape; the "squishy" foam type that's about 2mm thick. I applied the tape around the outside edge of the badges, and used "Gorilla Glue" in the center.
Anyone familiar with "Gorilla Glue" will know that it foams up and expands as it cures. So, when I woke up the morning after applying the badges to the center caps the glue had found a way to 'squeeze' it's way out of a couple of cracks in the tape. It vaguely looked like there were buggers on the assemblies at first glance, but when I picked one up I quickly knew what it was. It was easy to break off the excess glue.
I think I'm quite pleased with out it turned out.
My current plan is to have Bridgestone Potenza RE960AS 195/60-15 tires fitted to the rims in about 2 weeks time.