I'm not saying the RM cars wouldn't be ok on the sports tires. If we're going after realism, who in their right mind would spend the money to upgrade a car to a race car and then slap some street tires on it to go to the track? Only PD would do this and I really think it has to do with the Japanese bias that exists in the game. I won't get into the specifics, but there are a lot of things in the game that is slanted toward the Japanese. I will run whatever tires we are given as everybody has to run the same. I will say that the further it gets from realistic, the less interested I will be.