Help verify what I think is right in terms of Back Space - 66 plymouth

[Garceau]

Everything in my brain tells me I am correct - but I am ordering wheels this morning and down to a couple pair and need to verify.

Current wheels on my 66 are 15x7 with 4 inch BS.

Front wheels have lots of room and thats not an issue, as we are aware the back wheels are a bit tighter in these cars....

I have room towards the frame rails and I may need to get 15x8 wheels..... my math and drawings tell me that a 15x8 wheel with 4.5 inch BS should put the tire in as near the same spot (I know the different width will effect sidewall width slightly)

this is correct?

 

[gtx6970]

Mine are 15x7 with 4.25 BS. on both cars
And I have plenty of room both sides.

 

[gtx6970]

On the flip side.

I have 15x7 torque thrusts and they rub the wheel lip BAD in the front on turns.

But i dont know the BS on them

 

[Garceau]

On the flip side.

I have 15x7 torque thrusts and they rub the wheel lip BAD in the front on turns.

But i dont know the BS on them

View attachment 1327524

What size front tires ya got ? They look a bit wider than mine, but could just be the pics.

 

[Don Frelier]

You can fit a 15" X 8" with 4.5" backspace on the rear but it's tight you need good bushings and variations between wheel wells could even cause rubbing on an uneven surface.
245/60 tire I wouldn't go any larger mine do fit fine.
I have 15" X 7" Ford wheels on the front with a 215/65 tire they too have zero offset I believe.

 

[33 IMP]

Assuming your 15x7 4" bs wheels are aluminum, they are really 8" edge to edge, so with 4"bs they are zero offset. The 15x8s, also assuming aluminum are 9", 4.5 bs means they are also zero offset. So the tire will be in the exact same spot.
Whether or not you will have tire clearance will depend on how big a tire you want to run, and how much room you have now.

 

[gtx6970]

What size front tires ya got ? They look a bit wider than mine, but could just be the pics.

245.60.15

They rub on turns.

This pic ive changed them down to a 215.65.15 and they clear fine

 

[Fran Blacker]

Had L60' 15 X 7 4" BS rubbed on corners. 4.5 BS your 8" width takes the 1/2" you gained. wonder if 4.75"?
I had to use a bottle jack to jack rear spring down to get tire in wheel well, and carried it with me, never had a flat.

 

[R/T Boy 67]

If you wanted the outside of the tire to be in the same spot it is now, and all of the 1" extra width to move inward, then you would need a 5" backspace. A 4 1/2" backspace would move the outside of the tire a 1/2" in both directions.

 

[Nxcoupe]

On the flip side.

I have 15x7 torque thrusts and they rub the wheel lip BAD in the front on turns.

But i dont know the BS on them

View attachment 1327524

If I were to guess, I'd say 3.5", just by the looks of them.

 

[33 IMP]

On the flip side.

I have 15x7 torque thrusts and they rub the wheel lip BAD in the front on turns.

But i dont know the BS on them

View attachment 1327524

If I were to guess, I'd say 3.5", just by the looks of them.

Those look like eights on the front to me.

 

[Nxcoupe]

Those look like eights on the front to me.

Could be the offset giving that impression?

 

[gtx6970]

Those look like eights on the front to me.

Just measured them

8" outside to outside. They are marked 15x7 which would be about right on an aluminum rim

 

[Lemon_Belve]

I tested different Options.
Front tire Size 235/60 15
Rear tire Size 255/60 15

Car: 66 Belvedere II

With 15x7 torq thrust D 3,75" BS Front, no rubbing
15x8 torq thrust D 4,5" BS rear, rubbing every Corner

Now with Rocket racing Fuel Gray 15x7 4,25" BS Front and rear, no rubbing
With 0.5" spacer in Front, no rubbing

Here the TTD with rubbing

Here with Rocket racing