need wheel spacers

[Bradley3054]

So i need wheel spacers but idk what size to go with i was thinking 1/2 inch because wont need studs. Wanted to see your all recommendations, my old 37s did the same also but i didnt care about them they were used and cheap but now have 39 xml military tires with new rims 16 xd hoss with 4.56 and at full lock turn the side knobs rub the front side of my springs and edges of the knobs on tire is what catch not the whole knob. also my new hub cabs wont go on because they bottom out on my hubs by quarter of inch short looks like. What you all think, not trying to stick them way out there just minimum amount i can to erase all rubbing.