VAP

at various places on the track and they are 4mm wide. I'll sit 2 side-by-side at 10-12 places around the track, ie; inside apex, outside apex, mid track down the straight etc etc. I then try to move one while driving the course but not disrupt its mate. Once you master that you try to miss them with the front tires and move only one with the rear tires. Bob Bondurant taught this technique in his drivers school at Sears Point in the early 70's when I was prepping for my SCCA National license and later my IMSA license.