IM getting closer to buying my new wheels. I'm thinking of running 305 45 22 on my fx2 with 2" drop shackles. Should I go with 22x9.5+ 15 or 22x9.5 + 30. What's the difference?

 

stock wheel offset is +44
those 30s will push the wheel out further
the 15s will push the wheel out further still

assuming that you have stock size tires on your current stock wheels and...
taking into consideration the change in rim width and tire width...

the +30 wheels with the 305s will have the outside sidewall stick out 1.15" more than stock

the +15 wheels with the 305s will have the outside sidewall stick out 1.74" more than stock

to be clear i'm not saying the tires will stick outside the fender 1.15 or1.74, i'm saying they'll stick that much farther than the current stock wheels/tires.

i have zero experience with dropped trucks so i can offer no advice on what will work clearance wise