Rim Help/Backspacing Info Needed

[Fatherflash]

Need help/advice from the team.

I have a 1972 chevy 1/2 ton long bed which will eventually be lowered, probably bagged with Porterbuilt suspension. Suspension is presently stock with original rear end installed.

I have an opportunity to purchase a set of used Boss 20 inch 304 rims with 255/35ZR20 97W nitto tires. I understand I should consider 40 series tires however, these are mounted on the rims and in excellent, almost new condition. I will likely swap tires eventually.

Rims are in almost new condition with damage to rims evident.

Seller is reporting backspacing on the rims is 5.5 to 6 inches. Rim width is either 8.5 or 9.5 inches.

Will these rims and tires fit on my truck?

Picture of rim with mounted tire is attached.

[sduckworth13]

5.5 should fit all the way around, I think 6 will be to much. Yes on the 8.5, not real sure the 9.5 will fit the front without some issues

[AZBIG1]

Will fit the front just fine. Too much BSing for the rear without wheel spacers. 1.5" or 2" spacers will get the rear where you want it. Shouldn't have any rubbing down to a 3" drop. maybe more.