Well, not sure if anyone else is reading this thread, but I thought I'd mention that I bit the bullet and picked up some Pilot Alpin PA2s today in the stock OEM 18" sizes. I realize that the PA2s have essentially been replaced by the PA3s, but unfortunately PA3s aren't yet available in 265/40R18 (or anything close). I considered going with PA2s in back and PA3s in front but I figured that this was not ideal and could potentially make the tires less effective than if they were all just PA2s.
Anyay, I got the rears at TireRack on close-out for a good price. Unfortunately they are already sold out of the PA2s in 245/40R18 so I had to pick those up elsewhere. I plan to mount them to my factory 18" wheels. Next year I'll either pick up a second set of OEM 18s for summer duty, or just get some new aftermarket or OEM 19s for summer use instead.
A gen-u-ine BMW eff-eight-zero with them tandem clutches in the transmission and that dad gum sun roof on the top-a da cawr.