Not sure why, but all the text didn't post. Glad I copied it:

I wanted to put together a reference thread on ZL-1 fender flares and compatible wheel sizes as I didn't find a ton of info out there and it could be helpful for someone. I will share a bunch of notes about issues and remedies, and hope it inspires questions we can add to the thread.

First off, if you already have flares on your car, here's something interesting to check. Measure from the door jamb to the fender edge on both sides. You may find that your fenders were eyeballed during install, and could be off by a not-insignificant-amount like mine - almost 1" along the length of the car. One of my flares was also positioned differently than the other vertically, which caused a discrepancy in the wheel-to-fender clearance.

Fender rubbing had been an issue for me as long as I've had the car. In the rear I had been running original US Indy Mags 15x10 with the standard 3.375 backspacing (I think that's right, will double check) on standard trailing arms. After years of abuse which thankfully didn't completely blow out the fenders, I had managed to wear away a decent amount of fiberglass on the back edge of the fender lips - both sides - using these wheels and 275-60-15 radials. The fronts were US Indy Mags 15x8.5, standard backspacing.

Woes me, after replacing the old diff in the car - which had side yokes that had worn down 1/4" on each side - well, the wheels were now another 1/4" outboard and the rubbing became very problematic. This is where I ran into another curious issue that after some research, established is fairly common on C3s. I was trying to raise the left side to address the rubbing, and noticed that I had to tighten the spring bolts down significantly more on the left side than the right in order to achieve level ride height. Currently I have the left spring nut tightened 1.5" higher on the left. I still really don't understand why this is, but through various searches across this forum and others, it's a common issue on C3's. I installed three different springs with the same results. Frame is reasonably straight and body mounts are not collapsed. I've learned to live with it.

So I had fiddled with things quite a lot at this point and mostly had everything running well with no rubbing. Then I ran into an issue with the front wheels. I had been experiencing consistent leaks and suspected a crack, but decided to remount the tires to see if it was a bead leak. Fast forward to some more alignment adjustments and stress testing, and I managed to blow out a front tire - bead failure.

I wanted to get the Indys off the car for restoration. Finding another set was untenable - they're scarce in this combination, partly because they don't make 8.5" widths anymore - so I decided to look into other options. This was when I came across a post from @Black72GTS running some Aeros. The Aeros come in a wide range of backspacing, which meant I could bring my rear wheels in just enough to clear the fenders, while avoiding any rubbing on the inside - the parking brake clip is just a little under 1/4" from the rim/tire.

I went with Aero 58 series. Fronts are 15x8 and 3" backspacing. Rears are 15x10 and 4" backspace. Same tires transferred over, fronts are 225x60x15, rears are 275x60x15 BFGs.

It's true the Aeros have a different center dimension, but I was comfortable using hub centric rings. While waiting for the spacers on order, I found an appropriately sized piece of stock to use as a feeler to check the wheel positioning on the hub. With some care, you can line things up appropriately to avoid wheel vibration.

This seemed simple enough to write up but there's probably a ton of detail I'm missing, and now I'm a few beers in so I should cut myself off. I hope there are follow up questions and we can add to the thread to benefit other folks who happen to find useful info in here. OK attaching some pics now.

​​​​​​​

 

I run 275-60-15 drag radials on 9.5" rima without flares tucked in nicely . Youd havé to Get alot more tire to need flares.

 

I have those flares. I run a 295-50-15

 

Sounds like you have around 4" backspace then? Seems reasonable.

There would be a lot of variables related to installation of ZL-1 flares that would affect how much additional clearance it offers. In my case, it was the hand I was dealt.

 

What backspacing? How heavy of a spring do you run? Mental math says your tire has a slightly smaller overall diameter.

I'm running a 360 lb Van Steel spring and it almost seems not stiff enough. With the spring bolt nearly out of adjustment, the tire could still hit the fender under full load. Still dialing things in, hope I don't run out of adjustment.

 

If memory serves me right you'd be correct, I think they're actually 15x8 with 3.375 back spacing. I have the heavy duty 7 leaf spring and I put in a rear spring lowering shackle kit from https://www.southerncarparts.com/c2-...ackle-kit.html
it hooks up pretty good.

 

And the reason I installed the lowering shackle kit is because I had the same issue, under heavy acceleration my left tire would rub, I replaced my side yoke, checked alignment etc , the shackle kit gave me more adjustment. Rear of the car sits even now.

 

Does the shackle lower the mounting point for the spring? It's super reassuring to hear someone else who has fought gremlins like these.

 

No it still mounts to the differential in the normal fashion, it just lowers the spring at the outer ends.

 

This is from Google images, I'd show you an actual picture of my set up but it's at least 427 degrees outside, I'm over weight and I just opened a beer

 

;D

I think I misunderstood, I've got essentially the same setup with 8" adjustable spring bolts.

 

I like your car with a 18 inch wheel you could run a 315/30/18 on all 4 with 5 inch back space .

 

do you have any engine pics i run my 02 sensor the same way .

 

Making flares fit properly is a lot of work. I was hoping to attach flares w/rivets or screws of some kind.
Any advice in the forum?

TIA

 

IMCO the best way to get the look you're after is to fit the flares to your wheel and tire combination.


2 very different looks. The blue C3 the wheel wells are full. The bottom C3 the tires are tucked in more. Just depends on what look you prefer.