don't most ATV sand tires recommended 5psi or less? take a look at you side wall. i run 2.5-3 psi front and 3 psi rear on the quad. i run my mini truck 8psi front and 6-7 rear. i run my suburban 8psi on all corner, but i have rolled some tires off the bead with the big tank. and i run my bike on flats half the time. i start the bike out at 2psi front and rear but before the end of the weekend there just flat.