I'm looking to put some RS6 style alloys (prob 18inch, not sure if 19 will fit) on my 2004 A4 TDI Sport. Looking into what is available, there seem to be alot of these wheels with different off sets (35-45) and stud diameters (100-112). My current standard wheels state off set is 45 and are 17inch. I'm not sure how to measure for the stud diameter (poss being a bit thick), I've measured the distance from centre of one bolt to centre of opposite and don't get the 100 or 112 which seem to be the measurments given for these aparently geniune OEM alloys. Basically the look I'm going for is very much the same as with the B7 S lines, which I believe are 18inch. Don't know if these will fit straight on but assume so. Can anyone tell me what offset and stud diameter I need and if there is leeway on the offset, if so how much? Thanks in advance.