20" (R) & 18" (F) for 67 C10 SS. Looking for best width and back spacing
 

Ant thoughts for best tire width and wheel back spacing on lowered C10 with a 20" wheel? Going to 18" in the front with Helix Mustang II IFS.

Re: 20" (R) & 18" (F) for 67 C10 SS. Looking for best width and back spacing
 

You'll prob have different size needs depending on how much drop the truck will have.
Another thing that impacts the possibilities will be if any other mods are done to the truck (willing to mini-tub; what year/width rear end; off the shelf wheels or built to spec).

Re: 20" (R) & 18" (F) for 67 C10 SS. Looking for best width and back spacing
 

Standard 12 bolt with updated axles and diff. C-notched in back however new coil-overs will mount on end of DIY trailing arms with about a 4.5 -5 drop. Yeah willing to tub slightly.
Hoping for 10" to 10.5" of tire in the rear and fill up the wheel wells. frame is set up with 12" of ground clearance in front to top of frame and 23" in the rear.

Re: 20" (R) & 18" (F) for 67 C10 SS. Looking for best width and back spacing
 

Do you know the track width of that IFS as compared to OEM?

Re: 20" (R) & 18" (F) for 67 C10 SS. Looking for best width and back spacing
 

Assuming the rear end is the original '67 to the truck, it's slightly narrower than the later 71-72 housings which allows more clearance on the outside edge when using wheels that have 'off the shelf' type back-spacing.

A popular 18/20 combo once upon a time was:
18x8 w/a 235/50-18 @ 27.25" or a 245/45-18 @ 26.7 tall.
20x10 w/a 295/40-20 @ 29.3 tall.

I like taller tires personally & try to keep the heights similar to what the truck came with which is usually about 27" minimum. Since you're willing to mini-tub, a 10-11" wheel will not be a problem out back. That 295/40 mentioned fits a 10-11" wheel nicely. Anything in the 275 up to 315mm range will work on 9.5 - 11" wide wheels.

Tire selection will likely be a limitation though. There are not as many manufacturers making the 295/40 as there used to be. That limit hurts even more when trying to match the front & rear tread pattern in different diameters as well.

What tire options were you considering?
What wheels were you considering?

Re: 20" (R) & 18" (F) for 67 C10 SS. Looking for best width and back spacing
 

Fleet side or Step side? Is "SS" for Step Side?

Re: 20" (R) & 18" (F) for 67 C10 SS. Looking for best width and back spacing
 

I assumed it was a stepper....

Re: 20" (R) & 18" (F) for 67 C10 SS. Looking for best width and back spacing
 

id like to know what you find out too. Im building a 1968 with the shorter rear end. I just updated everything with new axles, etc. need to know backspacing and offset so i can order a set of wheels. no tubbing for me and jsut want to "tuck" into the rear fender oh so slightly.

Re: 20" (R) & 18" (F) for 67 C10 SS. Looking for best width and back spacing
 

For the rear, most of the 20x10 wheels you will find have approx 5.5" backspacing and most of the 20x9.5 will have approx 5.25" backspacing.

With the narrower rear end you find on the 1967 and 1968(like I have) you would most likely want 20x10 with 4.5 backspacing and 20x9.5 with 4.25 backspacing, to make them look correct. I'm pretty sure my 20x10 with 5.5 backspacing were going to rub the wheelhouse inside the bed.

I found a thread on this message board where people were using 1" spacers to make them work, and man do they look good like that.

I had the opportunity to get a rearend off a 1972 have have now changed to that, before I have the truck running.

Those 20x10 with 5.5 and 20x9.5 with 5.25 fit so many more trucks. Likely 71-87+ So that is what the wheel manufacturers focus on.

You could always have wheels custom made with a different backspacing, but those wheels are around $1000 each. If I ever go that route. I'll likely swap back in the 1968 rear end and make careful measurements with the truck fully assemble to make sure I get exactly what looks best.