I had a set of 15x7 Vette rallys I test fit on my 66. I didn't like how close they came to the rear fender lips. (with 205/75-15 tires). A 3.5 " offset gives you 3.5 towards the lip compared to 3.0 with standard 6" rallys.
There are some 15x7 rallys that were specific to 69 z-28 Camaros that had 4.0 backspacing which gives you the proper distance to the fender lip. 4" backspace is about the best you can do without having interference to the e-brake clips on the trailing arms.
I don't deal in backspacing, but their offset is -0.28". Beware that other Chevrolet seven inch Rallys used on other models have different offset. Because of their negative offset you can't put on a tire that justifies a seven inch wheel without shaving the horizontal fender lips on a C2.
The six inch Rallys have +0.60" offset and with a 215/70R-15 tire will normally have sufficient clearance to not hit the fenders. Setting front camber at zero to a bit negative and rear camber at at least -0.5 degrees should give more than adequate clearance. The only other issue might be front frame rubbing at maximum steering lock, but since you probably won't be at maximum lock above parking lot speed, it's not a big deal.
Thanks for all the info. I've noticed that there are rally wheels with different back-spacing. I thought that I could get a 15x7 rally with a 4" back-space but I was concerned that a standard 68 trim ring would not fit. I measured the back-space on my knock-offs and they were 4"
15 x 7 's off a Monte Carlo will hit the brake cable brackets, the tire sidewall may rub the brake cable and the outside of the rim will hit the end of the spring. Believe me I know. If you jack the car up to allow full extension of the suspension and try turning the wheels the wheel weights and I think the rim itself WILL hit the end of the spring. On the road it is OK. On the front 15 x 7 will rub the frame behind the front suspension. The bolts that hold the steering box in place take a nice polish from the sidewall.
I run the 32-spoke Western Wheel Turbine wheels with center spinners (the look of Corvette knockoffs at a small fraction of the cost). They are 7 inches wide with 3-3/4" backspacing and fit my '64 perfectly with 225/60/15 tires. (They were used on Z-28 Camaros but mine are for Chevy/Ford/Chrysler with "slotted" lug holes.) I need to use a thin wheel spacer in front to clear the cailpers on the disks and even then, I can wipe the steering box carrage bolt shiny on a locked left turn.
Don't/didn't, you run 7" vette rally's and 225/70's on your '63? Seems like I remember you saying that.......
Yeah, but I had to trim the horizontal fender lips and front bonding strip. I did this back in 1968!!!, but I DO NOT recommend that folks do this today. I'm the original owner, and I doubt if I'll ever sell it unless they pry my driver's license away from me went I get senile, and I probably won't sell it even then - just park it in my living room.
I do have to admit that 225/70VR-15s on '68 seven inch Rallys look (and work) great. The wheel cover "Ben Hur" spinners stick out beyond the bodywork and can take out the kneecaps of daring pedestrians who stand on the curb if I clip the apex real tight. ;) The big wheels and tires really give it a hunkered down appearance.
at one time i purchased a pair of rallys 15x7" from summit.
ordered a backspace of 4" these work well. i ran a 225/70x15 white wall.
one side is close and on hard bumps it rubs.
i recently upgraded to tork thrusts. custom part number CL205.
in 15x7 with 4" b/s all around. i am using 225/60x15.
still close on the same side. may be just my car. but other than that they look fine. no other rubbing that i can tell.(autocrossed twice now).
rubbing is on drivers rear. if i went with a 215 or 205 i'm sure it would be fine. but since there is no serious rubbing, i'll stick with 225.
d.s. in n.j.