Rim offset

[gbatey]

I'm looking at the American Racing rim AR708 in the 17 or possible the 18", it has a 5.5" offset, Will these fit on a 77. I would really appreciate any help from members before I buy these. I here that 4" to 4.5" is what works best. Thanks Gene

 

[Whoaa]

No.

You need 3 1/2", or a maximum 3 3/4" backspacing to fit proper. Anything more and it creates all kinds of problems, and specifically on a 77' model.

17" wheel diameter work great, and do fix a lot of clearance issues.

Without getting into a big and complicated explanation, the wheels that work best are 17" diameter, 8" to 9" wide, with 3 1/2" of back spacing. These wheels fit nicely with 33" to 37" tires with 12 1/2" width rubber used on a 76/77 model

EDIT: The OP used the term offset, and in my comments I used the term backspacing. These two terms mean different things, and sometimes are *wrongly* interchanged to add confusion. Here's a neat little diagram http://www.4wheelparts.com/tire-wheel-package-guide/wheel-offset-backspacing.aspx

 

[englewoodcowboy]

If it is back spacing you are referring to then they will work with the use of a bolt on wheel spacer, as noted before optimum BS you want is 3.5 to 3.75, if you have a 4.5 BS wheel then you can bolt on a 1" wheel spacer and be at 3.5.

 

[JefeAZ]

My setup is a 16x8 with 0 offset and 4.5" backspacing. I know 77 is whole different animal though

 

[englewoodcowboy]

My setup is a 16x8 with 0 offset and 4.5" backspacing. I know 77 is whole different animal though

The main issue on the 77 is the disk knuckle, the tie rod bar is turned in towards the wheel for some odd reason in Fords design. The F150 knuckles and FS Bronco knuckles the tie rod bar is straight just like the drum brake knuckles. Switching to larger rims or to F150 style knuckles solves the issue with the 77's.

 

[Knuck]

I am running 15x8's with no wheel spacers on my 76. I have never had an issue with caliper clearance. Not sure what backspace my wheels are since is been forever ago that I bought them.

 

[Apogee]

The main issue on the 77 is the disk knuckle, the tie rod bar is turned in towards the wheel for some odd reason in Fords design. The F150 knuckles and FS Bronco knuckles the tie rod bar is straight just like the drum brake knuckles. Switching to larger rims or to F150 style knuckles solves the issue with the 77's.

If you're referring to the steering arm on the knuckle, the 76/77 EB knuckles are designed to have an improved Ackerman angle, so I would think that is most likely the reason Ford chose to make the change. Ackerman is a function of the steering arm angularity and the wheelbase.

 

[MyOriginal66]

I'm looking at the American Racing rim AR708 in the 17 or possible the 18", it has a 5.5" offset, Will these fit on a 77. I would really appreciate any help from members before I buy these. I here that 4" to 4.5" is what works best. Thanks Gene

Wether it's cut or uncut will make all the difference here. 5.5 is a little much for most but with a 7" wide wheel and a 10.5 or smaller tire they should work on a uncut. See below about turning radius. 4.5" BS will work and fit depending on tire on a uncut in 7" or 8" wide. It'll also work on a cut but the tires will be more inset to the body. Because your thinking of running a 17 or 18" wheel, the '77 knuckles shouldn't be an issue.

Most aftermarket 17's are 9" wide. With a 12.5 tire they should fit with no issues at 4.5" BS on a cut bronco except rubbing the radius arms. You can buy aftermarket arms (duffs or bkg) that will help or adjust your steering stops. As stated above, 3.5-3.75" BS is more common on cut broncos and will get the tire to stick out just past the flare.