Originally Posted by Display_Name
I'm praying it's the contact patches or they'll be big heap o'trouble.
The odd flip side (bad choice of words in a conversation about high speed driving, I know) is that to an observer in an outside frame of reference the tops of the tires would appear to be moving at 400 mph while the contact patch portion of the tire (hopefully) is standing still.
I thought this thread was dead and buried. Yes, it's the contact patches of the tires. The fact ocurred to me one day while watching a video of a half-track vehicle moving at a good clip. It was quite obvious that the part of the track planted on the ground had zero forward speed while the rest of the track was racing forward at twice the speed (of the vehicle) to take its place.
Congrats to Display_name for coming up with the answer!