Rex:
I think you have been reading my pre build notes (lol). We both have heavy road racing backgrounds so much of what I base my car design around, comes from Formula cars.
Originally, I had planned to use those dragster skinnies just like I did on my first car. I switched to the 18X4.4X10 aircraft tire after a short discussion with Stainless. Rob has far more experience with tire and wheel combinations on Bockscar so when he compared the two tire/wheel combinations, I listened. These 18" aircraft tire's need to be shaved so I believe there will be an aero improvement over stock. I have already begun my whining campaign to enlist help from Stainless to shave two tires. It is kind of an ugly, time consuming mess so I may have to ratchet up my whining intensity.
I am very interested in the McBeath three part study completed on a 1992 Swift FF. From what I remember of my FF and FC days, a good Cd for that vintage car was in the .40-.45 range so it would be hard to make too much improvement. As you may already know, I began my Lakester project with a 1984 Reynard FC chassis. Rear rocker suspension is stock and quite aero. When I talk with Maurer this month, we will be discussing how to hide as much of the rear uprights as possible. The upper rocker has a rounded leading edge but does not taper. Half shafts will be the big issue from an aero standpoint. When first putting pen to paper, I was assuming a .40 Cd, 7.2 sq. ft. frontal area. As it turned out, I will have a 7.4 sq. ft. FA, should stay under 2000 pounds and hope my Cd is .40 or better. Woody may be doing some initial CFD work for me to establish a few baselines. From there, decisions can be made as to what changes will yield best bang for the buck.
Your car will see the salt before I do. I will be trying hard to make the September USFRA meet.
John