I am not an expert on R7's, but my understanding is that R7's generally fall off after about 6-8 heat cycles. So, I would think that those tires could be used for practice or testing, but they typically wouldn't be used in a race.
What is critical is how they were broken in and used. If they were not broken in properly or abused (over heated), then they could be completely gone with those few heat cycles.
They don't have a lot of value but maybe $75-150 for the set of 4.
Used Hoosiers