I need some help guys

[Zefhix]

We're running the corvette Y2K rims on our 70 Chevelle but I'm not sure how to calculate the size adapter/spacer we need for the front wheels without physically having the car here. The rim is a OEM spec 17x8.5 up front and we'll be running a 255/40 series. I have to order the spacers now, anyone have a thoughts on what a safe bet would be? Is 2" too much?
I appreciate the help. I can't seem to find detailed specs on the backspacing of the Vette rim so I figured I'd turn to the expert egg hunters here. Thanks in advance!

[Q ship]

Hey Keith, how are things going? Been meaning to PM you, but things are always hopping.

Anyways, I have C5 wheels, but they're the wide spoke "wagon wheels". The measurements should be the same, but I have no proof of that. On the 17 x 8.5's, the backspacing is 6 7/8". For the Caprice I was going to use a 1 3/4" adaptor, I haven't had the chance to measure out the Nova. Using that size adaptor gives you a final backspace of 5 1/8", for comparisons sake.

Sooo, where's the car at?

[Zefhix]

Hey Keith, how are things going? Been meaning to PM you, but things are always hopping.

Anyways, I have C5 wheels, but they're the wide spoke "wagon wheels". The measurements should be the same, but I have no proof of that. On the 17 x 8.5's, the backspacing is 6 7/8". For the Caprice I was going to use a 1 3/4" adaptor, I haven't had the chance to measure out the Nova. Using that size adaptor gives you a final backspace of 5 1/8", for comparisons sake.

Sooo, where's the car at?

Supposed to be on its way to paint & body but we just got delayed a week with the promise of the same completion date....we're down to the wire over here freaking out! Thanks for the reply, the 6 7/8" measurement was the majic number I was looking for. Seen Harshman around yet?

[Q ship]

Seen Harshman around yet?
No, I've been bad and haven't called him yet. Brother is in town this weekend, then school starts.....I need a week off work to catch up!!

[slowcamaro]

https://static1.pt-content.com/images/noimg.gif

56mm- offset 6.8"- backspace

These wheels? Im running 2" adapters on my 3rd gen f-body. Im going to have to have them milled down(to about 1.7-1.75") after the c5 brakes go on though. Car needs to be lowered more.

as far as 2" being too much, i dont think so, but one recomendation, if you are getting them coated or painted (or ordering them that way) get the adapters done the same color and you'll never know they're there.



245/45's

[Zefhix]

Pretty close to that..thanks for the comments! I did the math and ideally i'd want 1 7/8" but 2" is close enough that I can mill to perfection. :)




https://static1.pt-content.com/images/noimg.gif

56mm- offset 6.8"- backspace

These wheels? Im running 2" adapters on my 3rd gen f-body. Im going to have to have them milled down(to about 1.7-1.75") after the c5 brakes go on though. Car needs to be lowered more.

as far as 2" being too much, i dont think so, but one recomendation, if you are getting them coated or painted (or ordering them that way) get the adapters done the same color and you'll never know they're there.



245/45's

[Blue70]

How did you come up with 6.8 backspace?

Am I doing something wrong?

56mm offset on an 8.5" wheel, so
56 divided by 25.4 = 2.204724409
8.5 wheel divided by 2 = 4.25

so 4.25 + 2.204724409 (positive offset) = 6.454724409" backspace

I am running 8.5" Y2K Wheels with 255/40's on the front of my Camaro.
I am using a 2" adapter which gives me a backspace of 4.45, but I don't know what you'll need on an A-Body

[Q ship]

When you use offset measurements, you only go to the bead seat of the rim. When you measure backspace you are measuring to the outer lip of the rim. That adds about .3-.5" to the measurement.

[Zefhix]

yep...bead on those rims is.25"....Skulte says 6.8" as well so 2" should be perfect. Actually, it has to be because I just ordered them! I'll let everyone know how they fit and then update the wheel database.

[Blue70]

Ahhh
Cool..
I figured it was two against one, I had to be doing something wrong :icon996: