Sorry if this is hashed out many times before... I did make an attempt to search.
I am looking at using 15x8 with 0 offset on my Z. I have (coil overs) and standard ZG flares. I am looking at using the bolt-on adapters/spacers and think 20mm or 25mm will work for the rear and about 15mm for the fronts.
I measured about 6" from the rear drum to the edge of the flare (car was not at the correct ride height so it will be less then 6" (closer to 5.5" I think) when it's set correctly.
The reason for 15x8 is there seems to be better options new and used in 15x8.
Thanks