as my understanding from a long, long time ago, the tire speed rating is for a constant speed for a given time.
now with that said, going [way ?] over that for a short burst, such as in drag racing, the tire will be ok.
this is just my personal experience using VW tires on drag cars of all classes, sizes, and weights, a long time ago before speed ratings and weight classifications were thought of. in other words, if it held air and looked good, it was good to go. i know better than that now.
your mileage will vary.