I think you will be just fine.
I drove my dodge 2500 hard with my Lance 855s from Seattle to Anchorage. If there was ever a time that a tire should have blown or an axle snapped, it should have been then. I have driven the Denali Hwy (130 mile gravel road) a few times loaded with no issues. Tires and trucks are rated below what they are capable of for obvious reasons. I wouldn't let the numbers or the safety specialists on this forum scare you. I realize I could invest safer equipment, but I don't give a crap. Take my advice with a grain of salt because I'm lucky to be alive; I grew up with led based paint, never wore a bike helmet, and played with lawn darts.