I just recently bought some 245/70/17 Nitto Crosstek tires.They inflated them to 38 psi cold. I have always been the 32-35 psi type guy. I never haul or pull anything with my truck,besides me. Opinions on running them at my psi,factory,or what they inflated them to?

 

Looking at the Nitto site, that tire can handle 2205 (on a truck true weight carrying ability would be about 2000) @44 psi (actually 35). As that weight is the bare minimum for your truck, you need at minimum 35 psi. They did a decent job with the pressures they put in when mounted. Leave it.
My guess is the factory was 35 and the OE tires were Hankooks. As for 38, you do not get any extra load carrying above 35, but you do get better handling with less sidewall flex.