Back spacking for 20's

i was wondering what backspacing would be needed to get a 20 to tuck on my 91 b2200. I am comfortable with the othe aspects of building the truck just now the rims

proper offset and backspace depends on width. Offset is the distance from the wheel centerline to the mounting surface, a +10 would be 10mm closer to the front edge of the rim when measured from the centerline of the wheel. BAckspace is measured from the back of the wheel to the mounting surface.

So without knowing width, you'd run into some problems. For example, a +39 offset 7 inch wide wheel will tuck like a mother, a +39 8.5 inch wide wheel will not. A 5 inch backspace 7 inch wide wheel tucks, a 5 inch backspace 10 inch wide wheel does not. Most wheels you find in 6 lug will be +35 but at least 8.5 inches wide. You'd need closer to +59 for an 8.5... almost a full inch more offset...Most 8.5 are 4.5 inches of backspace, you need closer to 6 on that width.

Your best bet is to have custom offset 20's made by the billet companies, or redrill/change your truck to 5 lug. There are a lot more wheels availible in high offset/backspace for 5 lug, and better widths too, someone recently was talking about a 20x7 in +40, that would tuck like crazy on a mazda.

But remember that you cant go looking for a wheel based on offset or backspace unless you know the width that offset or backspace is based on.

back spacking huh..ha ha.

you did'nt mention if your bodydropped of not which plays a major factor because of the way the body tapers.

anyway i suggest at least 7" backSPACING on an 8.5 for the front if your bodydropped to the rockers.

Yea it is going to be body dropped with 4x4 sheet metal layin rocker the rim width is probably going to be 8.5. I am working on getting enough lift to turn. There was a mazda on the cover of the feb 03',04' MT he had 19's with a 42 offset and they tucked nicely with 2wd metal.
thanks for the help

notch into the frame (front ) as far as you dare to and move your bag inward as far as you can, this will help a bit with lift and it will help keep the upper ball joint away from your bag when aired up.
slam bag rs 62...highly recomended.
it will lift up high enough to lock up those ball joints.

i think that i am going to fab some control arms up with a spherical bearing in them to help. As far as notching the frame i assume u mean to get it to lay out?

first of all meant to say is that the rs62 will give you more than enough lift to turn.

and as far as notching the frame (up front)and moving the bag inward, this is for aired up reasons it has nothing to do with being layed out.
it would be cool to have uniballs.
especially on the uppers.