Drag Radial Tire Pressure

Hi all:

I have 235/60 15 M/T ET Street S/Ss on the Dart. Got it to the track for Test and Tune yesterday and they did not want to dead hook. Best 60' was 2.19 (high 14 second car).

I would love to to go to school on what tire pressures have been successful for the experts.

TIA