I am running 17 by 9.25 with 5.5 back spacing on 45 series in the rear (with Hotckis). I had to add 1/4 inch spacers to avoid chunks of rim and tires being taken out on the passenger side inner wall (some drivers inner side also). I ass-u-me I had the correct sizes from all the posts on here, but I was wrong. So, make sure u get at least a 5.75 backspace if using my setup on a 68.

Also, bringing the caster to 4.0 in the front made a world of difference. BTW, the 4.75 backspacing in the front (17 by 8) with 235's work perfectly.

well great to hear, and i agree about how much increased caster helps handling

but, when you add a spacer, technicaly it is the same as having less backspacing
so you should have gotten 5.25" backspacing in the rear

thanks for the info

You're right. I stand corrected. I wasnt sure how that worked.

I'm not up on the "bigger" wheels and what fits. The measurements I got with a stock axel and drum brakes on a stock body/wheelwell was...

wheel mounting surface to inner wheelwell 6" and wheel mounting surface to wheelwell lip 5".

I run a 15" combo and need to account for the buldge.

doug,
how wide are your rims?
i would think you just need to center the rim in the available space
say that you have 8" wide rims
and an 11" wheel opening
so you have 3" and i think you would want equal space on either side so 1.5"
that would make 4.5" BS? Dont know if thats right but i makes sence to me and makes 1.5" on either side for tire bulge

Whether you're running drums or disks on the front and rear will also make a difference. If you're spending megabucks on wheels, the only sure way is to measure, then measure again, and measure once more for luck. Then sleep on it and measure once more.

Also let's not forget to measure BOTH sides. It's not unusual that on these 35+ year old cars that there is not the EXACT same amount of room on both sides. That's very important when fitting max sizes when there is little room for error.

Also let's not forget to measure BOTH sides. It's not unusual that on these 35+ year old cars that there is not the EXACT same amount of room on both sides. That's very important when fitting max sizes when there is little room for error.

Good advice...more often than not,the rear end is NEVER centered in these cars.

Measure 4 times,cut once.

400Bird, 15x8's with 4.5" bs is right on the money of what I'm runnin'.

Yea, there was more "contact" of the inner well on the pass side for some reason. With a spacer, I driving around like a madman and havent scraped since... It turns on rails now, but VERY stiff. i also think i have a close ratio box, because it turns TOO fast.