According to the Bridgestone tire people whose tires I run they are essentially small versions of their normal car road racing tires. I have never been told they have a speed rating but are built to run on the 250 single and twin cyl 2-strokes used in super karts. I have never in all my years at Daytona seen, experienced or heard of a tire failure. I have heard that a laydown kart like mine but with a twin cylinder 100 hp engine as used on the sit up superkarts has done 165mph in a test session at Daytona. In the WKA Unlimited 1 & 2 class in which I run laydown karts are restricted to one 250 single cylinder shifter engine. Mine has about 60hp. The 100 hp twins are restricted to the sit up super karts which are as about as aerodynamic as a brick. I do know that the super karts chew thru tires and at Daytona one of the reasons single cylinder laydowns beat the twins is because the twins tires often don't last to the end of a 30 min race. According to Don Bootes, who owns S & G Industries and who designed and built my Dominator, the bodywork was designed for him by a Bonneville racer by the name of Nolan White or his son I can't remember which, specifically to be fast at Daytona. My kart was his personal kart which he raced to numerous IKF & WKA National Championships.