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.

