Yeah the difference is so minimal. If you aren't in an extreme sprinting event and don't already shave your legs and head, don't bother.
But as long as we're speculating, what about a vaccum? Lightest filler possible! You could make a tire out of carbon fiber, line the outside with a tread, and suck the air out so its a vacuum! No real shock absorption there. But for many sprint races I'm sure they have a very smooth track anyways.