My attempt to use C5 rotors with FSLI calipers behind R15 wheels is a no go. I knew the spoke clearance on these wheels was tight, but thought I could overcome it with wheel spacers. The pic above is with a 1/2" spacer and the caliper is still hitting the spokes pretty bad.

I'm thinking I can get by if I use a Wilwood rotor instead. Does anyone know the measurement on the offset on these rotors? Or the difference in offset between the Wilwood and C5s? I know the C5s have a pretty shallow offset in comparison.

I'm really hoping I can still use my brackets by running a spacer between the caliper and bracket to push the caliper back further, but I need the specs to know what I'm working with.

It seems that few people have been paying attention recently when I've said, "contact Scott at Big Brake Upgrade." In the thread linked below, another member had a similar issue to yours, and Scott helped him solve the problem, without trying to sell him anything, as explained in the initial post of that thread. The thread goes on with continued support for Scott. I'd suggest you contact him. He's a great guy. He will help.

https://www.thirdgen.org/forums/afte...e-upgrade.html

I have C6 front brakes which are very similar I think. Outboard face of rotor is about 7/16" offset from wheel hub, and rotor is about 1.25" thick. So the centerline of the rotor is located about 1" smack dab from the wheel hub.

Oops. After reading this again I realize I answered a question that wasn't asked.

"I'm really hoping I can still use my brackets by running a spacer between the caliper and bracket to push the caliper back further, but I need the specs to know what I'm working with."

I'm assuming you mean that the bracket is the caliper mounting bracket..... Because it's the caliper that is interfering with the wheel, and the caliper mount is responsible for positioning it, the mount will have to be moved to accommodate the rotor with the right offset - if you want to keep the wheel and it's position in the wheel house.