When you road race, the tires come apart in big and small chunks. Circle track cars throw the rubber to the right side of the track. Road racers throw it just about everywhere.... If you are behind the car, those flares keep rubber from flying back into the person/car behind you. If you race an open cockpit style car, that rubber will fly off and into your helmet. It will also fly into your radiator, air venting, and many other places, causing different issues. It really is a necessity for that style of racing!