Just an aside, and sorry to Tom if this is cluttering his thread, but if I were an active CM competitor and owned a FF, I'd be thinking long and hard about petitioning the SCCA to allow some different wheels on the car, in the goal of having better tire options available.
FC wheels are very readily available on the used market at low costs and would bolt right on to a FF. The larger wheel would safely allow you to run FC front tires which are available in other brands, reducing the dependency on Hoosier.
-Mark