I finally narrowed down the wheels I want for the Camaro. Here are the specs
18x8 with 4.540 BS
18X9.5 with 5.290 BS
Bore is 72.591
Any reason a square setup with 275/35-18 would not work on my Camaro. I assume it will be about flush.
CARID says the 18x9.5 will not work on the back, I think it should be fine.
They say the 18x8 is fine on all four corners. Im on the fence. Plus I want to be sure on the tire size.
245/40-18 would be correct if I ran the 18x8's?
Thanks for some input. Oh yeah here are the wheels.

US Mag C-TEN -U129

 

If I were you, the 9.5" wheels with the 275-35 tires would be the only way to go since they should fit with those specs.

 

The biggest concern is if I upgrade front brakes to a LS/LT/Corvette setup, will it push the 18x9.5 out too much?

 

For Illustration purposes this is or was ChevyKens car with TT2 17x9.5 wheels with 5.5 bs, C5 brake upgrade with a 5mm spacer and 275/40 tires. The backspacing with the spacer and big brake kit would come out to about 5 inches. The 18x9.5s that you want with a big brake kit would stick out a tad farther than that.

 

"For Illustration purposes this is or was ChevyKens car with TT2 17x9.5 wheels with 5.5 bs, C5 brake upgrade with a 5mm spacer and 275/40 tires. The backspacing with the spacer and big brake kit would come out to about 5 inches. The 18x9.5s that you want with a big brake kit would stick out a tad farther than that."

Thanks. Any more that that would just be too much.
I think I will stick with the 18x8 in front.
Here are pics of some US Mag Ramblers / 18x8 in front and 18x9.5 in back on a third gen. These wheels have the same backspacing as the wheels I want.

They are both memebers here. Hope they dont mind me using their pics.