Okay so I got the rear tires; mounted and weighed them to compare against my old set up:
Old: Volk GTS 19x10.5 + Hankook Ventus RS3 305/35/19 = 59lbs
New: Enkei RPF1 18x10.5 + Nitto NT555 DR 305/35/18 = 50lbs
I think thats a nice weight reduction in rotating mass. Here's what it looks like now: