I read the wheel fitment thread and I'm still having some issues figuring out Offset. I get the concept but I'm not sure how to properly set it up. I want my tires flush with the fender or maybe 1/2" outside.
I found this fantastic site (https://tiresize.com/wheel-offset-calculator/) but I am also not sure what the stock offset is.
Further help, with the wheel offset, would be great.

I'm planning on running all four either:
255/35/R18
245/35/R18
245/40/R17

From what I can see, a positive offset will set the wheel back into the car whereas a negative offset will push the wheels out. I thought it was the other way around.
Also, would a 0mm offset set the tires flush? If so, then the stock offset must not be 0 but a rather large positive offset.

You need to factor in the width of the wheel also. A 17x7.5" wheel with 35mm offset will fit different than a 17x9.5" wheel with 35mm offset. And why would you want the wheel to stick out 1/2"?

I really don't. What I meant was it is fine if it's not entirely flush.

I run 245/35 R18, 9" wide , +22 offset on my 90 N/A and it looks like this

THAT'S what I'm looking for. I was checking out some other setups as well (https://www.fitmentindustries.com/wheel ... &year=1991) and figured that would be best option too.