Fallen RT 660 fitment
 

I’m running RT660 245/40 17 on a 9 wide 6ul and I’m getting a pretty good rub on the front wheel well that I did not get with the yokes. Also what tire pressure is working for everyone. I know it set up and course sensitive. I believe I have between 3 and 3 1/2 negative camber up front. I have less rub after I removed the camber and crash bolts from the front. On a low speed 49 second course , I found I had the best turn in at 25 psi up front with good rear grip at 27/28. 25 sounds too low and I don’t want t destroy my tires. Grassroots Motorsport tested them on a ND Miata and found 28psi was best. What is everyone else’s experience.

You need at least 7mm spacers in front.

What offset for the wheels?

17x9 6UL so +40.

Maybe try offset top mounts for more camber? Wouldn't go bigger than 3mm spacers if using stock length studs.

For pressure, I aim for ~35psi hot at the track. Or ~26psi front 28psi rear stone cold. In my experience most 200tw radials are fairly pressure insensitive within reason...

If I used a spacer, I would upgrade and lengthen my studs. ARP

Where in the wheel well are you rubbing?

My guess is the usual suspects.

Camber from the top hats is what you want. Camber from bolts bring you closer to the suspension. What's your ride height?

With +40 offset, Versus Steering Rack Limiter Kit will solve the rubbing. 1 spacer on each side is enough.

Before removal of the camber bolts, top of the wheel wells under heavy braking, After removal. I’ll post picture of of the rub. Forward of the coil over . Ride height is not crazy low. I have a 1 1/2 l gap wheel well. I’ll measure. Sorry on the way out to work.

I'm running 28 psi square, that was faster than 30 and was also good based on surface temps and apparent tire patch contact. I tried 26 but it didn't really feel better to me and wasn't faster, at least when it's at least 70 outside. I didn't think to try something lower the first couple events this year, given where you live that may be a factor. Gonna be plenty warm this weekend, tho.

I do get a little rubbing at the front of the wheelwell, but nothing too bad, however I have +35 wheels.

I currently have 255/40R17 660's on +40 6ULs. -3.8 camber up front.
I only rub on inside fender well at full lock. Not sure why you would be rubbing while braking.

I run same pressure setup as my Yoks, pyro'd the tire (autocross use) and everything looks good.
Cold: 27F, 26R
Hot: 28-29F, 27-28R

I recently ran a session on 255 660s and had no noticeable rub. I'll be monitoring it as I spend more time on them though.

17x9 +35 with 4 degrees of camber.