I'm going to Mason-Dixon Drag way for their final Test & Tune of the year and this time I have drag radials

I'm going to run spare tires up front and I'm not sure how to set the PSI on this set up.
The Drag Radials are BFG G-Force and the size is 275/40/R17 and the spares are stock size T145/80/D18. Also do I need to change my wheel/tires size with my predator or will it make a difference ?
Thanks guys