I'm about to order some new wheels for my 67 and I'm definitely going with 15x10 but need to know if I would be okay with only a 5" backspace. Want to at least run a 295, would love to run a 325 at times. Do I need to go with 5.5" of backspace or am I good with 5". Any help would be awesome, thanks.

 

Nobody knows for sure? I see for the later models like 70-72 guys are using a 5.5 inch backspace but not sure if it would be similar for a 67

 

I am not sure if a 5.5 inch backspace on a 10 inch rim would work on the rear of a 67 Cutlass. On my 442 I have 8 inch rims with a 5 inch backspace. The tires are 28 inches tall and 8 inches wide tread. I would say they are close to a perfect fit as far as centering the wheel and tire within the wheel well.. Maybe someone else knows if your combo will work on the 67.

 

I ended up with 15x8 on the back of my 67. 4 inch backspace 0 offset. 255/60R15 tires with a 10 inch section width. Not what you are planning, but I need the extra height to clear the wheelwell. Clearance to the inner wheelhouse is ok on my setup, but tire height will make a difference.
Tim

 

Yeah after some more research I think I'll be going with a 15x8 with 4 inch backspace and a 275/50/15 tire. Sounds like it will easier to fit and will have a smaller section width than the 295 on a 10 inch rim. Though the actual tread width is the same as the 295

 

That's a pretty small OD tire, only 25.8". Consider a 275/60-15 (28" diameter) or, if you can find them, 275/55-15 (27" dia).

 

With 10" and stock width rear, you can run 4.5 to 5" BS; subtract an inch for 8" wheels. BTW, I have steel wheels in both widths and the offsets that fit my 66.

 

I have a 66 442 and I am running 5.5" backspacing on my 15 x 10" rims with 275/60 drag radials. I wish I would have went with 6". I will get pictures later this evening.

 

Here are some pics of my 275/60-15 Drag Radials on 15 x 10 rims with 5.5" backspacing
DSCF2485_zps09a988f5.jpgDSCF2487_zpsea23b7dc.jpgDSCF2490_zpsbb045837.jpg

This one is a little deceiving,
there is about 2.5"'s clearance.

DSCF2494_zps9504faca.jpgDSCF2504_zps16b88aa2.jpgDSCF2510_zps1afc91e8.jpgDSCF2518_zps16096a43.jpg

 

Rob, it appears that your rear is wider than stock. On my two 66s with stock width diffs and 30x9 Hoosier slicks, they would hit the frame with 5.5 to 6" BS.

 

It's possible, I haven't measured the width. The rear end came from a 67 Cutlass Supreme I ran across in the junkyard about 20 years ago. What is the correct width back plate to back plate? I will measure this tomorrow.

 

Not to be one to jump in on the dog pile, but I would agree that the 5.5 with wide tires would most likely hit the frame. Are you sure about the width of your rims? An 8 inch rim measures 9 inches across the top.

 

I bought them brand new from Summit. 15 x 10 back 15 x 5.5 front.

 

I run a 15x8.5 with a 3.75" backspace, -25mm offset and P275-60-15 tires on mine. 15x6 up front with P225-70-15's.

 

Here's what I found. My memory is not what it use to be. My rims are 15 x 10 with 5" back spacing not 5.5". The rear axle is approximately 55" between backing plates. With this setup and running 275/60 drag radials I have roughly 2.25"-2.5" of clearance between the tire and the inner fender. With the wider rims my tires are pretty striaght on the side wall. My last set of tires were 295/50's and I never had a problem with intereference on the inside. On big bumps or with a load in the trunk I would occasionally rub on the outer lip.

 

IIRC the stock rear was 54.25" wide and your photo is consistent with your width and BS.

 

Any time you get a wider rim,you can go in as much as you go out,to keep it centered,or else we are back to the 70's & disco graphics.

Having a stock wheel on the car,with the car down,will show you how much room you have between the sidewall of the tire,and the frame,and the sidewall to the outer wheel lip.You can't use a bare rim because the tire goes out beyond that.

You also need to take into consideration as to how much body roll your car has.When the body tilts or rolls to one side,that wheel is not only going up,it is also going inward,due to the suspension. If you make things too tight,and you have excessive bodyroll,you will start cutting tires or rubbing something.There is a wide variety of rear suspension components to reduce excessive body roll.40-some year old bushings & a swaybar won't do it.

 

Does anybody have an issue with clearing the lower rear shock mount or any part of the suspension when going 5-5.5" deep on backspacing with a 15. That was one of my concerns, it seems like it might barely clear but not sure.

 

With a stock rear and stock shock location,5.5" is the deepest backspace that you can go with a 15" diameter rim. The bead of the rim gets real close to the lower shock mount.
A larger diameter rim could go over it,but the tire would hit the frame anyway.
For those that have the 64-65 cars,with the narrower rear,5" is the deepest you can go without hitting the shock mount.