Stock tires not sure what they are. I have a 2014 grizzly 550I usually run 4 psi with 27s, sometimes even lower. If I didn't have beadlocks or if I had smaller tires I would run higher pressure to make sure the bead stayed on and to protect the wheel more.
What kind of tires do you have? Bias ply and radial react to pressure a little different.
Exactly.4 to 6 psi works for most, with some running lower and a few like me that a little more.
Your tires and riding conditions play a big part in what works best for you.