I think my wheels have a 45 offset... anyways, I'm not sure, but it's a high number. They're 8" wide. When I put them on I felt like the fronts had some poke and the rears sat way narrow. I looked up some forum posts and people generally got between 10-20mm. The eBay default size is 12mm (probably a good number) and I chose 15mm. I just wanted them to match. I think it came out good @ 15.
this is before the install I'm just holding a spacer against the tire
Now I deal with it being painfully obvious that the camber is mismatched ... maybe made more obvious by the car's geometric shape