69 camaro wheel selection help with ride tech suspension and wilwood brakes

[rb69]

I currently have boss 338 wheels on the car and have installed ride tech's 4 link rear and tru turn suspension not mini tubbed. Car has wildwood 4 wheel disc brakes. 18x8 on the front with 225/45 and 20x8.5 and 245/45 on the back.

Looking at changing to 18" all around. Using back space & offset calculators to compare the fitment of new wheels to how the old currently fit (rears are tight).

From what I've been reading is that a 9" or 9.5 rear wheel with 5.5" of backspacing should clear using a 275/40 rear tire. Calculator shows it different. Moves it towards the inner some, but pushes it out towards the fender more. With the 20's I have nearly 7/8" clearance on the inner section.

I have been using rocket attack and several of the us mag wheel spec. to check sizing.
I have a pair of 275/40/18 stuck in the wheel housing now without wheels, while it's close it would work with the right wheel.

Sorry for the long post- I know this combo has been done probably 1000's of time, but i'm struggling to get it.

Thanks

[elwaupo]

Hey that was a good posting. I just put a Tru-Turn set up on my 69 Camaro this year so wheel and tire clearance is something I’m keeping in mind. Last year was an EFI conversion, next year will be a 4 link rear suspension and who knows about the following years to come. It’s a fun never ending project. ��

[elwaupo]

What size wheels and back space are you currently running now and are there any clearance problems? I’m looking to run 17” or 18”