I have 18" X 8.5" +48 SSR Comps and they are just about flush with the fender. They look nice when you look down the side of the car (STi). The tires (245/40-18) barely clear the fenders with 1.3 degrees negative camber.
An 8.0" wide wheel with a +42 offset would fit with the outer lip in almost the same position. A 235 width tire on such a wheel should fit quite nicely while a 245 would barely clear like mine.
That said, a +42mm offset is really not right for Subaru.
EDIT: My SSR Comps do NOT stick out as far as pics from Kean.