We have done our homework on these tires and you will immediately see the quality. Not another knock-off, not another copy cat, not another repackage of someone else’s products. From top to bottom these tires are exclusive to RC4Less. Furnishing the highest quality tires for RC Racers was our first criteria. Then taking this quality and making it affordable. Our “C” series foam is Exotic Rubber foam with a lower rubber content than the Natural Rubber foam. "C" series tires are the choice for most carpet racing. Durometer ratings are indicated with each compound designation.