they space the wheels out farther from the wheel opening, making a fuller look.
since these wheels are already 1/2 inch wider, it is not really neeed IMO.

Is it possible to get these anywhere these days? I did my lazy man ebay and googly search and have had no luck in three days of searching :(

Here ya go!
 

Found on ebay this morning.... x5 22 | eBay

oops!!!
 

sorry... try this link instead; BMW X5 4.8is Wheel Package 22 in. Alloys - NEW! - eBay (item 190522465155 end time Apr-19-11 06:56:34 PDT)

They look nice, but my opinion would be 20's. under all circumstances including looks.