"Oh boy", is all I can say. No, I can say more; trust me.
Pearldrummer7, I can't find your
build thread so I have no idea what you are doing or trying to accomplish. I have read some of your posts, but I still don't know the critical aspects of your build and I'm not going to do all the digging/research to know.
Tire specs are everywhere. Phil's Tire Service has lists of all the major players. I cut and pasted into Word all the ones of interest to me so I can refer to them instantly.
I think the wheels you've ordered are a good choice for the price, quality, availability, etc. I do not care for the thin ring. I have PF01s on my STi. However, for saving a couple of pounds per wheel, my Wedssports are (appx.) twice the money and may not come in 5 X 100. I went with 17's in the rear, as well as the front.
Why buy wheels that likely won't work and then have to spend the money for spacers? Why haven't you settled on tires?
225/245 seems to be the norm for the track and ST2. I squeezed 275's on the rear of mine (in a test fit) but mine is far from a stock FFR rear suspension. I will start with 225/245 slicks.
Why do you want such big tires? On the track you have to heat the rubber and they might be too big for a fast warm-up and might never get up to proper operating temps.
Perhaps I'm missing something, but I feel like you've got a lot of 'splainin' to do.