got it, thank you for the info. I'm going to 18x8 et45 .. so I'm figuring about ~6.5mm closer to the strut. I have the 18" stockers (18x7.5 et50) on right now, going to TSW Nurburgringconversion spacers are made with min 15mm as far as i know.
depend if your wheel has clearance in the back spacing then you would need to figure out how thick of spacer you need.
also depend on offset of your current wheel.
not like you can just throw some 1" spacer if your current offset on the wheel is too low already.