I join Shelby friends for a track day at MSR Cresson on worn Sport Cup 2 tires, using them one more day before replacing them for an upcoming planned complex track event. It was my 2nd time running the full 3.1 at MSR-C and it had rained prior to our first session, which made it the slickest track I have been on to date! The track surface improved on subsequent sessions, but the tires were losing grip as the day progressed, especially the rears. The mishap happened on session 4 and was captured on multiple high-def cameras. I went off track high-speed and into a muddy creek. It took some effort to get me out as I was pretty far off track with slick mud complicating the extraction. The video finishes with a synopsis of the event and lessons learned.