wheel offset explanation needed
 

so what the heck is the offset on my iron cross wheels?
i have searched and cant find it anywhere

from what i gather 114.3x4bolt 17x7s will fit on my 280zx with between a zero and +10mm offset

the way i understand offset is that it is the distance in mm from the centerline of the wheel so a positive offset is moving closer to the outside of the wheel and a negitive offset is moving closer to the hub
is this correct??

if that is correct than +42mm offset wheels will fit with 35mm adapters and that would be an offset of +7mm right
thanks in advance
--daniel