77 Chevy PU Backspace and Rim Size

[LBJ]

Going to be putting some new wheels and tires on the 77 Bonanza one day not too far out.

I want to get some basics before I start looking. What is the backspace for a 1/2 ton five lug wheel? What rim size would work on this truck with 18 inch aluminum Rallye Wheels? 9 inch? 10 inch? I believe the new Chevy bolt pattern will not interchange with the older ones (5 x 4.75" I think). Is this correct? I have to see what tire pattern (60's, 50's 45's, etc) will look good on the truck, too. It's a bit hard to visulize tire size and width. I have been on the site where you can make your own setup, but it's still hard to determine what will and will not rub on the frame before hand.

Right now, I am looking at Vintage Wheels 18 inch aluminum Rallye's. I like the look and they go with the era of the 77. Not cheap, but not off the dial either.

Thanks for the help.

LBJ