Backspacing question

[CC69Rat]

Realizing most people (with 20's) run 20x8.5 up front with 5.25" Backspacing .. 255/40/20

4.5" drop seems to be the norm. I am about to drop my GMC and that's around where I'll be too.

I want just a touch more sidewall up front. I have 255/45/20's ready to go. I am about to buy my wheels and I'm down to two. The issue is the ones I really want only come in 20x8 with 4.5" Backspacing.

So .. in theory if it were an 8.5" wheel instead it would be the same as 5" Backspacing. Just shove that extra width to the back. ..

However: 20x8.5 with 5" Backspacing vs 5.25" BS ? Would that be a show stopper? Would that extra .25" to the outside make a huge difference? Any pictures down the side of a truck with 20x8.5 5.25" Backspacing on a 255/40? ~4.5" drop.

I just want to see how much room it has. .. An 8" wheel will pull my 255/45 in a little so the section width will be about the same as a 5.25" BS 255/40.

Think it would be ok?

Thanks.