Generally your pushing it to get 15" wheels on.
You will probably have to think about doing something like this to it for a start:



Correct me if I'm wrong, but modifying your struts has nothing to do with the wheel size, width yes, but it depends on the offset. You'll have to check that first. If your desperate to have rims with the wrong offset, you can try some of these:


( _steve_ 's pics )
Having said that, YAJOKN has some pretty big rims on his. (17's ???)