What comes first wheels or rear end???

[Green72]

I've searched until my eyes bleed. I am embarking on a build that will test my skill set for sure. I would like to know what a good procedure is to determine rear end width vs wheel/tire combo. I will be starting from scratch on the rear of a 1967 GTX. To me it's kind of like what came first the chicken or the egg. I will be moving springs inboard and widening tubs. Also, it will be a 4 link. I would like to hear from some of you on what your order of operations are, do you determine rear end with and choose wheels or do you choose wheels then have rear end built to fit? I'm probably over thinking it!!
As usual thanks to everyone this site is absolutely gold.

 

[gkent]

Are you narrowing the frame or just mini-tubbing to the exising frame?

 

[radical rob]

If doing 4 link, don’t need to move springs. Their position will determine how wide rear axle and whether will need to be narrowed. Wheels are after all that is done. May need custom backspace.

 

[70chall440]

I completely agree with both comments above. The only caveat would be if you had a specific set of rims/tires already that you "just had to use".

 

[6PKRTSE]

Agree with everyone. However, I was able to get a great deal on my wheels and I went the opposite route. We narrowed my Dana, mini tubbed and relocated my springs inboard with Caltracs and split mono leafs to fit these wheels and tires (315/60/15 drag radials).

 

[33 IMP]

Tub size and frame width will determine how big a tire you can use.
Rearend width will determine how much wheel width and backspace you need.
So, rearend first. Unless, exactly as 70chall440 said, you've got wheels/tires already that you have to use.
I'm using these on a four-link car, but the car has a tube chassis.

 

[#41]

do you determine rear end with and choose wheels or do you choose wheels then have rear end built to fit?

You do both at the same time unless you want to risk having to pony up for custom offset wheels. If there is an exact wheel that you want plan backwards from that using known wheel size & offset for the width of the axle you are having made.

 

[dvw]

Too many variables to start with the axle first. Once the wheel well dimensions are decided, then it's time to chose the tire and wheel combo. You may find one wheel well tighter in some spots than the other. Don't forget about ride height as many 1/4's get narrower at the top.Back spacing isn't always available to fit your exact needs. Use a piece of tubing with a center slip joint. Weld some circular plates to the ends with holes of the correct bolt pattern. Bolt the wheels on. Then slide the slip tube in/out and get the dimension you are happy with. Next determine how thick the rotors or drums will be. Lastly get the axle offset dimension from housing to flange. You now have a complete working dimension for the axle housing. When in doubt make it 1/4"-1/2" narrower overall. You can always space outward. But if it's too wide, your in trouble. Also a heads up. If you are using stock frame rails. Trim the outer flange at the top outer and weld the corner. The frame rail is wider at the top than towards the bottom. I've done more than few. Two years ago swapped up from 10" wheels to 12" wheels on my 64 with stock frame rails. Obviously the axle was already in the car. It took some very careful measuring and some thin spacers and trimming the uppper lip to get it all to work.
Doug

 

[Green72]

Are you narrowing the frame or just mini-tubbing to the exising frame?

Mini-tubing to existing frame

 

[Green72]

Thanks for all the help. Time to go figure it out!!

 

[gkent]

Mini-tubing to existing frame

THAT is your starting point and the limiting factor of tire size. You will get a tire with a 15" cross section in there - something like a 29 x 15 x 15. Now you have to pick your wheel width and backspacing. Personally I like the mounting face to be in the center of the wheel. Once you've decided that you can bite the bullet and buy the tires and wheels. Now set them in the wheelwells at ride height and adjust your clearances and measure your width mounting face to mounting face - this will be your total rear end width.

 

[6PKRTSE]

THAT is your starting point and the limiting factor of tire size. You will get a tire with a 15" cross section in there - something like a 29 x 15 x 15. Now you have to pick your wheel width and backspacing. Personally I like the mounting face to be in the center of the wheel. Once you've decided that you can bite the bullet and buy the tires and wheels. Now set them in the wheelwells at ride height and adjust your clearances and measure your width mounting face to mounting face - this will be your total rear end width.

I agree. My wheels are 15"x12" with a 6" back space. The tires have a 15" sidewall width.

 

[Black_Sheep]

It seems like high end car builders dial in the stance and wheel/tire combo then build from there…