sfsvettes

I havea 65 with stock fenders ( no flares )and I have re-located the emergancy brake cable brackets to the top of the trailing arms....
Anyone know what the largest rear wheel I can fit under the car with out rubbing or breaking something ???
I would like to go to a 17 or 18 " rim size but not sure about width or backspacing...Thanks

greendot

Back in "the day", some guys could run G60/15's on the 69+ 15x8 wheels, but most could only get F60's to clear their fenders. The point bing that there was some variation between bodies so it's ahrd to give a for sure answer, but if you get the dimensions of those tires it's a good starting point to compare 17 and 18 inch tires to. Those wheels had a 4" backspace as I recall. You can go a little more backspace wiht your relocated pb brackets, but not really a lot. The big deal is that a slight rub now would be a friendly surface, not tire to sharp edge bracket. Actually, I think that with a 17 or 18" wheel, the bracket would not have been a problem as the bracket would have been within the wheel cavity. So, IMO, a safe guess is max of 8.5" wheel with 4.25 backspace with tires with a diameter/width not more than the F60/15.
There is a local fellow that currently autocrosses his 63 with C3 aluminum wheels, stock fenders. I need to check what size tire he is running.

69autoXr

I believe that local fellow is running 245/50-15's on later model C3 slotted aluminum wheels.

Gordy M

The max you can run on 15x8 is a 245/50x15 tire on 8.5's you will start sawing the upper fender. On 225/50x15's I could just hit the upper fender on 8.5's at a high banked track like Spartan. Thats on a C2. The C3's had more clearance. Also, ride height was a variable depending on how new the rear spring was.

You could increase ride height also by shimming the spring bolts.

greendot

Keeping in mind that he is going to use a 17 or 18 " wheel and pick his backspace, not be stuck with the offerings of olden days, he should be able to go to an 8.5, don't you think? For sure if he can go 4.5 backspace, then that entire 1/2" is inboard and not a problem. I just can't be sure about fitting 4.5 backspace.

hose head 63

Looking at the responders, they're all local fellas. Did someone call a competition commitee meeting?

At the autocross I'm running 225/55-15 Hoosiers on stock 8" C3 wheels. Fender lips are trimmed, camber is around 1.5 to 2 negative. On the street I have run225/60-15 as well as 245/50-16. Those 245's were squeezed down onto 7" rims to get the section width to fit. Wheels have near zero offset so spacers were required on the front to minimze frame rub. Still rubs some.

The street tires are smaller OD than original so tranny drive and driven speedo gears were changed to keep the meter relevant.

Personally, I am no fan of wheels any taller than needed to clear the brakes or suspension. It just adds weight for appearance sake. Also adds profits for wheel and tire manufacturers. However, top performing tires are getting limited in sizes even in 16's.

Your proposal for 17 will get you clearance on the spring ends, the next limiter after you moved the brake bracket. You are using the stock steel spring, right? Some of the FRP springs have longer / wider ends that might even bump into 17's.

You should have a hair over 10" from frame to fender lip. Check both sides. That limits you to 9.5 section width. A 225/55-17 gets you close to stock OD with 9.2 width on a 7" rim, 9.6 on an 8". It will still require some dial-in with wheel spacers to ensure clearance.

Whatever you do measure, measure, measure. There is just too much car-to-car variation to take any recommendation without close, accurate checks.

greendot

Thanks Hose Head, put my college training to use. You don't need to know the answer, you need to know where to go to get it.

sfsvettes

Thanks for the insight guys. I used to run that 15" set up with the hoosiers on my 69 with no worries but I don't want to take a chance on tearing up the 65 fenders. I guess I will venture down to the local wheel shop and get them to pull some measurments to get it dialed in.

Gordy M

Its not the size of the wheel its the diameter and width of the tire/wheel combo. The C2 had very little space between the inner lip and the trailing arm. I could run 245's on 8 " rims and just scape a little, on 8.5" they stated wearing down the inner lip. On back spacing I believe 4.25 was about max without hitting the front sway bar.