quick question guys... I have wheels that are 17x8.5 with an offset of +25mm. By adding 2" spacers (50mm), I have essentially turned my wheels into a -25mm offset... correct??

Sorry if this is a dumb question, but i have never fully understood backspacing and offsets lol. I just like what catches my eye!

 

Yes. You will essentially change the backspacing from 5.75 inches to 3.75 inches.