I have a set of Roja formula 7's 18x8(+45) that I currently use on my Lexus is300.(planning on swapping 2 of them over to the front of the Z(if I can).
I purchased some 19x10 (+30 offset) in the same color and style for the rear of my new Z.

The question is:

Can I use a 15mm spacer up front with some nismo stud extensions to bring the wheels to the ideal +30 offset without having the wheel and tire bug out of the front fenders? I think it maybe possible because i saw and article in the Sport Compact magazine online issues that had a Z running 18x9 +42 offset up front with a 12mm spacer Essentially making it +30 offset. The Article:
http://www.sportcompactcarweb.com/pr...t_2/index.html

 

You would have been better off selling your old set and starting over. A 8" +30 is not ideal by most standards unless you like the stock look of the wheel really tucked. You would need at least a 25mm in the front just to make it look decent, IMO.

I had put 15mm spacers on my Formula 7's, 8" +25 and 10" +30. Essentially I was running a 8" +10 front and 10" +15 rear to get the look I wanted. Really I'm not a fan of spacers. Since you have the chance, do it right and get a better fit.

 

You think 25mm spacers would be safe? Would the tire stick out of the wheels well? Which studs would I need to upgrade to? The 50mm or the 60mm?

In that article they did the BBS wheels that way because, like me, they did'nt have a choice. Being that they don't offer the Ro_ja formula 7 anymore and getting your hands on even just 1 replacement(for a damaged one) is hard enough. They also did an interesting thing with the tire sizes. They are exactly the same front and rear. They have some pretty meaty rubber in the front with this spacer situation they chose. I need as much beef between me and these Memphis City road conditions to avoid a potentially chatostrophic lip bending event. Hence the reason for wanting to run an 18 up front as well as the fact that I already own a full set and it would be cheaper for me to just "borrow" them from the lexus.haha

 

The front wheel/tire will still be tucked with a 25mm spacer, no worries about rubbing/sticking out of the fender. Most 25mm spacers come with built in studs, simply bolt onto your current studs.

This is the 8" +25 and 10" +30 setup:


This is after I added 15mm spacers:

 

Go with AT LEAST a 25mm spacer in the front. We run wide wheels with low offsets in this camp. I'm running 19x9.5 +17 & 19x10.5 +18 for instance, and that's only average for aggressiveness.

 

Guys, this helps alot. Thank you especially 1nate7 for the pics. So I should be ok with what I plan to do,right?

In the words of that eskimo on that pontiac commercial years ago.."Wida is Better".

Hey, what size tires you guys think would look good with this set up whilest running the 18" (front) and 19" (rear). I want the height from rim lip to top of tire to be comparable up front and back. Keep in mind I want alot of tire between the road and my new wheels.

 

If I understand this correctly, it won't be possible if you try to keep the overall diameter even close to stock. The Z comes stock with staggered diameters, the tire sidewall in the rear is larger. You are going to exaggerate this even more with a 18" wheel in the front and 19" wheel in the rear. Less wheel = more tire sidewall.

I would run 255/40/18 front, 285/35/19 rear. That is about as wide as I would go on your wheel widths and the diameter is just slightly bigger than stock. It should keep VDC happy if you have it.

 

Do you think that if I through a 15mm spacer out back that the 285/35/19 would have rubbing issues on the inner fender?

I like how "snug" yours looked after you put the 15mm spacers on.