FWIW I had the 615s when they first came out, so pre-K, and they got greasy and scary when hot. This was on a 2400# car in the touge of Okinawa, no way in hell I ever heated those the way I have heated tires on the Camaro and Z06 here on real tracks. That's always stuck in the back of my mind. I know the compound has changed, but I never really hear of people raving about these tires for track days, HPDE, etc even if they are the Formula D tire of choice. I'd caution you about trying to get a contingency deal from Falken though, you'd be stepping on NASA/Toyo toes.