67' Chevelle and 18's

[ssx]

Hi,
I sold my 67' to a friend and he is wanting to change the wheels from 20's to 18's all around. Just wondering what is the correct backspacing for a good fit? He wants to run 18x8's front and 18x10's out back. (The car had 20's all around when I got it and I don't know what kind of BS the rims had, the fronts rubbed the fenders when turning though). Anybody got first hand experience?

[USAZR1]

I'd probably run 5" on the 8's and 5.75" on the 10's.

[bowtieguys]

I'll try to get my backspacing. I have 18" x 7" up front and 20" x 8" in the back. They fit perfect.I get back to you as soon as I can.

[gearbanger]

I have just odered 8's and 9.5s for my 67 GTO and I am getting 5's for the front and 5.5's for the back. I did alot of careful measuring and this should work perfectly on mine with no spacers. If anything, an 1/8 or 1/4" spacer on the back should fine tune it in perfectly. You want to make sure you get enough BS though. You can always space out, but there's no going in. :)

I used the frame in the back. I can use a BFH on the tub in places if I need to, but the frame is staying. I mounted and piece of aluminum angle to my lug studs so I could rotate it around and have something stationary to take measurements from. I took the overall size of the tire and subtracted the over all rim width. Then divided that in half. That is the "pooch" past the rim lip. Then I added 1/2" clearance and subtracted that from the distance to the frame in the closest spot. It was 6-5/8" on my car. So I subtracted 1-1/4" for the pooch and the clearance and got 5-3/8". So I am going with 5.5" backspacing on the rear.

On the front I used the same aluminum angle and I drilled holes in it at points where the rim edge will be and where the widest part of the tire will be and where the edge of the tread will be. I used 5/16 allthread rods to mock up a tire and wheel cross section, and locked them in place with a nit on each side of the aluminum angle. The I rotated it through and cut the wheel from lock to lock rotating it through at all places. If you really wanted to do something you could take out your front coil spring and compress the suspension up and make more checks. I just sat my car on a bottle jack right under the ball joint to get the suspension compressed the best I could. If I have interference in the front it will be the tire hitting the swaybar at full lock. I wanted the fronts tucked as much as possible so I wouldn't have problems hitting the fender lip.

We'll see. I post pics when I get them.

[gearbanger]

Another thing you need to know,

Rolled lip wheels are 1" bigger overall than the rim size. Stepped lip wheels are 1/2" bigger overall.

Rolled lip wheels come in 10" and are 11" overall , stepped lip wheels come in 9.5" and are 10" overall.