Rear wheel offset question

[Drice82]

i bought and laced a new 18" rear rim at 2.5 inch width, I realized after removing the original 16 I didn't measure the offset. I see from others that there isn't any offset but no mention as to which side that's measured from. Since this is a change from stock I realize there will be some altering but a start is always helpful. Thanks

 

[drewpy]

there's no off-set, that's it.