i do not believe that anyone sells these off the shelf. they are steel so they can easily be widened to fit your needs.
Are you sure you want a 4" offset?
http://www.speedywheels.com.au/images/wheeltech/measure-offset.jpg
"Understanding Offset
Fitting a set of wheels with the correct offset is most important. Yet, because there are two commonly used (but different) methods for measuring offset, much confusion reigns.
At Speedy Wheels we understand both the "backspace method" and the "centreline method", so a short explanation of each may assist you in selecting the correct offset wheels.
Backspace Method: Measure from the inside rim edge to the high point of the bolt hub. Distance "A" in millimetres.
Centreline Method: Measure the overall width of rim (Distance