20x12 wheels?

[1moretoy]

I have a 70 short fleet that was a step side originally. Coys are coming out with a 20x12 wheel and will be ready to ship in about 6weeks. I want to order a set. What backspace do I need?
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[1LIME69]

Do you have widended tubs or a shortened axle?

[1moretoy]

Axles are stock and yes I will widen the tubs
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[1LIME69]

I have 20 x 12 Billet Specialties. I went with a 7" backspace. I think I could have gone with a 6" backspace since my truck isn't slammed. I did add 5" to each side of my tubs. By my measurements if you had a 6" bs the inside of the wheel would just be touching the inside of the wheel tub wall. Thats not counting the bulge of the tire. So I would say you would have to widenen atleast 2" to not rub. If you measure in your bed 5" just works out the best when widening due to the ribs in the bed (in my opinion). Here are a few pics to give you an idea. The first is after I cut the 5" out and drilled the new holes. The other 2 are self explanatory. Yes the paint is supposed to be that dull. lol

[1moretoy]

Thanks for the pics and info. I have a wood bed so it might be a little easier to tub since I'm doing a custom bed floor. I think he said the wheels will be available with a 5.5 or 6.5 back space. I will call him to be sure
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[1LIME69]

Someone else might have a different opinion but I think 5.5" will be too much with the tire bulge. I think I would go with the 6.5". Is your truck lowered?

[Hart_Rod]

It kinda depends on the tire. I'm running a 31 x 16 on mine and had to go with a 7" backspacing (I have the narrow 67 - early 70 rear end). If you have the wider rear end (late 70-72), you will need at least 7.5 backspacing. BTW, what backspacing options is Coys offering?

EDIT: If you are going with bags, you will probably have to do some metal modifications to the "outer wheel tubs" as well as the inner.