More air will put more tire on the ground, wont be the fast way for sure.

If you want my opinion, and you did not ask for it but here goes. I can see from that pic you need a WAY STIFFER shock on the back of that thing. It works well but it is killing the sidewall. Tubes can also help, I don't think Hoosier makes a stiff sidewall that size. Mickey does and IMO just about every ladder bar car out there can benefit from stiff sidewalls and or tubes. Or better yet a stiff sidewall tire and a beadlock wheel. But just my .02 on the picture...