I want to change the wheels on my 2007 S4 B7 cab. I know there's been lots of threads on this before and I've tried to work my way through them to understand the option. I am looking at the Le Mans design (RS) wheels. There seem to be a number of options as these were used on RS4 were an S-Line upgrade option for the A4 B7 and were also used on the A6 and A3. With 19" and 18" sizes.

What I can't figure out is which of these is best option and how significant the offset (ET) is. As I undestand it the S4 18" wheels are ET38. The RS4 19" are ET29 so this means these stand out by an additional 9mm. The A6 19" variant are ET48 so would be 10mm the other way. The 18" S-Line upgrade version are ET45. The S3 ones are ET54.

Am I getting bent out of shape here (like lots of the wheels on fleebay!)? Anyone out there done exactly what I am trying to do and been through this process and can give me the benefit of their wisdom?