I am going to be getting some 15x8 diamond pro series wheels for the time being and was wondering what backspacing would work best with zg flares, i was thinking 3 1/2 but i'm not sure. Thanks.

I see no-one has answered this one for you. I don't have ZG flares but I do have custom steel flares at are 2 1/2 inch wider than stock. I purchased 15x8 with a -12 offset = almost 4" BS. My car is still in bits so I can't show you a photo of what they look like on the car (don't know myself). I purchased the rims based on measurement and calculations.

Lots say 15x7 0 offset fit stock. So I did the following calcs. 260z alloy rim that were standard with my Z are 5.5 with +18 Offset = 4" BS

Rim width - bead 2 bead offset BS FS

7 8 0 4 4

5.5 6.5 +18 4 2.5

8 9 -12 4 5 = 2.5 wider than standard rim with standard fender and close to 1" sticking outside the standard fender if 7" 0 offset will clear.

Hope this is of helps

Mike