Vertical scale is drag coefficient (CD) and horizontal is Mach number (M). At 0.9M, the CD was .35 with the faired wheels and support structure, but .43M with the final open wheel configuration. That would have been about our peak velocity in the mid-mile/kilometer speed traps, which was 660 mi/h. Instrumentation showed The Blue Flame was stable, as if on rails, throughout the high speed runs. In fact, tire wear was non-existent from the 24 runs. One rear tire was replaced when it skidded on braking, while towed in the service area, at around 30 mi/h and showed a tiny flat spot. The two front tires were replaced early when a slow leak (probably O-rings in the wheel) occurred in one. We just replaced both as a caution. The 4th tire remained on The Blue Flame for every run and looked new when we were finished. I believe Goodyear kept that one on display in Akron. We would have uprated the rocket to 22,000 lb thrust the next year and tried for Mach 1+, but, since we didn't own the car any longer, the sponsor put it on the exhibition tour and then "sold" it to the Shell Oil executive in Europe so we couldn't run it again. Now the shell of The Blue Flame remains in Sinsheim. So, 0.9M was it for The Blue Flame. Not too bad for a bunch of "cheese heads".