I did this one some time ago, was bored that day. 
It’s a 21" rim inspired by the rims on the Lancia Stratos rally car, (14" or 15").
Made in AutoCAD 2010. I don’t know how to export the model.
imagizer.imageshack.us/v2/280x200q90/673/HrrHhL.jpg
If someone with more skills than me is interested in putting this in the game later on, PM me.