ET question

ET is the position of the wheel center in relation to outer ring of the rim. So a “0” ET puts the center of the rim right in the middle of the outer ring (the lug mounting area) A negative ET puts more of the rim and tire towards the outside of the vehicle a positive ET puts more of the rim and tire to the inside of the vehicle. So your ET of 40 puts the wheel to the inside of the vehicle. All things being the same the -9 would move the outer wheel towards the outside of the vehicle by 49 mm from where the current wheel is.

Wheel Offsets Explained - Konig Wheels