Actually you are safe for more than that, briefly. The speed rating is for continuous speed and refers to the heating of the tire carcass. If you just zoom up and down again there is no heating, or at least not enough to cause problems.
I built a 427 Cobra replica a few years back, and it had S rated tires - mud and snow rated too - and I regularly blasted it to 130mph, just not for long. The Porsche guys in the motorsports club I was in used to laugh at the tires - until I beat all of them in the slaloms. Bunch of pansies.....
SRK, Your the BOMB The good old days B) B) B)