I've got a nifty set of hoosier dirt stockers in my garage that came with my new ITA car... problem being I have no idea what pressure to run them at?!?!?

I've heard only heavy rain, rivers running across the track, etc. for track conditions . Asuming that is the correct useage, what hot pressure should I be looking for?
Also, assuming those type of track conditions, how long should I expect they last?
1 hour? 2? 30 minutes?

thanks!
Marcus