Is the car setup to the specified ride height? Put the car on some blocks that match the specs for chassis height. Pull the wheels, shocks, and springs, and disconnect the roll bar - reinstall the wheels and fully cycle the suspension on each side thru its full range of motion including steering lock to lock - record findings. Reconnect roll bar and cycle both sides checking for any interference (can't imagine, but you will already be there) If you find trouble, correct as necessary.
I put a 225/65 on the front of mine. As a quick check on Friday I could not get a 3.5 inch block under the front tire when the front tire was against the inner glass in full bump - 15.5 degrees of LCA angle and the tire is into the fender.
With the taller tire (and the chassis at spec height) the LCA is around 6.5 degrees effectively reducing bump travel as the chassis is lowered with respect to the height of a 225 tire. In order to correct it, I need to raise the chassis or change stuff to get the LCA parallel to the ground when the car is sitting at spec height.
My point is not about my scenario, rather the physical limitations of the interacting parts which need to be understood to solve the problem.
If everything is perfect, do you have enough spring?
I have a feeling something is a miss in the setup.
If you really suspect the roll bar, you could disconnect it, zip tie it out of the way, and drive it to check it out (then put it on blocks and spend the day studying
).
It seems the car is pretty accurately built around a 235 tire - at least on an FIA. I would verify the front ride height first, if you have not already. On mine with a 235, the LCA was parallel to the ground with the chassis at spec height. If they are tipped up, you should consider raising the chassis height which will get you off of the tire and may, or may not, completely solve your problem.
If this ends up a double post - sorry.
chr