picked out the wheels for the truck..but need help

[SCOTI]

Rears could prob be 20x9.5 or 10 (whatever they offer) w/a 295-40 or 45. The 295-45 would be closer to your height requirement.

The fronts could go 18x8 or 8.5 (again, whatever they offer) w/a 255-45, 50, or 60. I'm pretty sure I've seen the 255-50 & that would be closest to your height requirement.

For front backspacing, I would go w/4.75 or 5". The 5" would be better for trying to keep the front track width even w/the rear. You'll need to trim the a-arm lip but that's pretty easy work.

For the rear, I can't say 100% because I've never played around w/a step-side to know just how tight clearances are..... especially if you've dropped it. My best guess (somewhat educated guess @ that) would say 20x9.5's w/4.5" backspacing. IIRC, the stepsides don't offer as much wheel well room vs. fleets. You could always mini-tub it on the cheap w/a set of fleetside tubs bolted in & trimming the bed-floor. That opens your choices up & I would then say 20x10's w/5" bs.

If you need help trying to measure all this out, I might be able to swing by @ some point in time.