I run on a small backyard track made of very sandy clay. As long as there is moisture in the track the clay holds the sand in place. The problem is when it starts drying out I start spinning the tires off the corners. The tires never make any heat. The track never takes any rubber. I run yellow Vegas that punch 34-38. I have been using Black Sand and Topaz during the week and let the tires cure for 3 days before using them. I need more bite.