Would they work on my rims? I'm not quite sure how they attach but if they would work I think I'll go old school and get some. Any Ideas?

From what I've looked at, they mount over 3 "nubs" on special rims. But there are some that mount to a spring clip that attaches to the lug or something.

i have these for my camper they attach to the lugs and would look cool with a buick center or whatever to customize the look. the only sticking point may be trailers are 5 on 4.5 and yours are 115mm which is 4.528in might be close enough.
http://www.ebay.com/itm/Trailer-Cent...95791422777524

and you may want to get outer trim, i had a similar thing on my old pickup and just went to the jy theres alot of vehicles, cars, trucks, vans that have a trim ring just kinda snaps in. the trouble was finding four alike. i ended up getting two from one and two similar from another and just keeping them the same on each side.

4.5 i believe is close enough at least thats how he ordered my rims. Those caps would probably have to be the route i take although they might make my car look a little truckish lol