Hey, been lurking around getting answers as I work on my build for about a year now. Finally finished with the rear QA1 install and working on the brakes currently. Looking to get some wheels lined up so I have them here when it comes time to get this thing off the jack stands.

My question is in regards to wheel offset. Here are the specs of my project currently:

Dropped 6" front with beams and springs
QA1 install in the back (front will be done next winter) which should allow me to get down to 7"
Stock bolt pattern

When I reached out to Detroit Steel about some wheels they told me 5" backspace for an 8" wheel. It is my understanding that "0" is 4.5" backspace on an 8" wheel. The wheels I am looking to get are these:
https://www.americanmuscle.com/musta...389252g05.html

I was looking at either 19x8.5" all around or 19x8.5" front and 19x9.5" rear

The 8.5" have a 30mm offset. with my truck being stock lug pattern I would need adapters. My confusion is in the offset. Im not sure I understand how offset translate to backspacing. I *think* a 30mm offset is essentially a 6" backspace. Is that correct? I want to make sure I get adapters that allow me to clear the tires front and back with the fenders. I'm also curious what tire size would be recommended to achieve this and not be too big/small. Was thinking 255/90 for the 8.5.

Attaching a current photo of the progress for anyone who cares.


Appreciate the help!

 

First off, nice work, looks good.
Im personally not a big fan of adapters but that may be the only way to get the wheels you want unless they do custom offsets. On the rear of my 62 I'm running 10" wide 15" wheels with 4.5" backspace and 275/60-15s with no clearance issues. If I'm calculating that correctly it's a -1" offset or -25.4mm. An adapter may get you close with 30mm positive offset, but I don't know the thickness of the adapter. That would be the first thing I would figure out. What is the best quality adapter for safety and how wide are they. On the tires for 19's I, personally, think a 28" tall tire looks best. Many run shorter. I found the staggered combo pictured seems pretty nice for a 8.5-9.5 combo. I would spend some time plugging in some different available 19" sizes on this calculator.... https://tiresize.com/calculator/

 

I was recently introduced to a much simpler way to tackle this problem. I asked the same questions to the wheel manufacturer, and he said ....... hold on lets simplify this for you. Tell me how far away from the frame do you want the back of the tire to sit, comparative to what you have? Thats it no hocus pocus no complicated formulas just that!!!!! What a relief ! and in the end I got exactly what I was looking for. For my application it worked . Maybe not in your application. Im interested to hear about the end result , please let us know.