Wheel back spacing (HELP)

[66farmer]

Time is running short for me. I need to order my wheels and I don't have the bed or the front fenders on as of yet. So I need some help from you guys.
My truck is a '66 short step-side 4.5" drop front and 6" in the rear. Stock rear axle width 5" on 5" bolt pattern, the front is 78 disc brake transplant. The rims I'm going to buy are Boss 338 18" front and rear. I want to fill the wheel well but I don't want to rub. Please let me know what has worked for you guys.
If you can only comment on the front please do.

Thanks for your help

[chevyrestoguy]

Go with the 18x9.5 in the rear. They have a 5.0" backspace, and they'll fit perfect. Go 18x8 in the front. They have a 4.5" backspace. They don't make anything narrower than an 8" in the 18 inch diameters.

If you order these wheels, ask the wheel guy if they'll clear the center hub of the front rotors. When these wheels first came out, it was a problem on the C-10s and guys had to either grind their rotors or run a spacer.

[66farmer]

Originally Posted by chevyrestoguy

Go with the 18x9.5 in the rear. They have a 5.0" backspace, and they'll fit perfect. Go 18x8 in the front. They have a 4.5" backspace. They don't make anything narrower than an 8" in the 18 inch diameters.

If you order these wheels, ask the wheel guy if they'll clear the center hub of the front rotors. When these wheels first came out, it was a problem on the C-10s and guys had to either grind their rotors or run a spacer.

Thanks for the info, I will check on the rotor clearance

[BR3W CITY]

I jammed a 12"+ wide wheel and drag rad5ial in the back with an 8.5 bs