Hey, I plan on running 18x9.5 (square) Konig Ampliforms with a +25 offset (6.2 backspacing, if that effects anything)
I will be lowering the car on Tein Flex Z coils.

With this being my first time buying wheels and dealing with fitment I am far from knowledgeable in finding the proper fitment.
I have been browsing the internet and the Fitment Industries gallery and for the life of me, (maybe because I'm just not understanding) it has not helped me one bit and everything I see just seems to contradict one another.

I'm hoping I won't need to run spacers, but if I need to I will.
If I will, what size spacers will I need to run? and with that fitment is it recommended to run any camber? And if so, what degree camber?

I greatly appreciate any help and feedback. I'm beyond ready to get this figured out and continue on with building the rest of my Z over the winter.

Thanks!

 

When you ask, "Will I 'NEED' to run spacers?", that all depends on what your goals are and what you are willing to do in order to achieve the "right fit".

So, are you going for pure performance gain or more for aesthetics (as in "flush" to fenders)? (Most people want both but if you are only going for a slammed look, that changes things.)

As such, for performance, that size will fit nearly perfect with a set of either square tires or staggered in upsized tires 245/40-18F & 275/40-18R. No adjustments to suspension nor fender modifications are likely necessary FOR THE WHEELS. But, you may need to correct the camber and toe depending on the amount of drop you set the Tein c/os at. General rule of thumb: if you drop 20-25mm, you will likely be OK without NEEDING to adjust alignment settings. More than that, recommended you install rear camber arms & offset bushings and adjustable FUCA (front upper control arm) to bring alignment back into spec. But the key is to be able to set alignment to your needs. Looks like you track the car (from the pic). It's nice to be able to set alignment for the track and return it to stock range for street/highway if desired.

If you are looking for a very flush fitment, you'll want an offset (on a 9.5 wheel) of around +15mm but, expect to need a fender roll to avoid interference, mostly on bumps and potholes.

My rec: Choose your wheel/tire setup (install and test) then lower around that. Finally, install alignment adjustment as needed. Honestly though, assume you will need to install alignment gear if for nothing else, to save your tires.