Since the concept of offset and backspacing tend to confuse people frequently (at least I witness this upon the forums I visit), I'm going to expand upon this, as it's rather vague. Offset is a function of the wheel width and in order to know the proper offset to run on a vehicle, you must know the wheel's width.
The point I am trying to convey is that a 40mm offset on a 9" wheel will fit entirely different than an 8" wheel with a 40mm offset.
This is a no-brainer to those of us familiar with calculating wheel measurements, but like I said, I have witnessed people's confusion with this concept and just wanted to try to clarify that post where I felt it wasn't clear. I meant no offense to your post, pektel.