being it is a heavy car you might go up on pressure. Wade Metzinger a member here spoke with MT at a recent divisional race. They had him increase his tire pressure, he was up as high as 20psi with his 68 Barracuda with no problems. It was 60 footing in the mid to high 1.4s IIRC. He also runs the 28x10.5 PBR

I have run mine at 17 and 18 PSI and my last outing there is a good shot where I have a lot of sidewall wrinkle so I am going to go up a little bit next time out and see what I have.