Well I have been rock crawling both ways. Not airing down is diffidently a bouncy ride. It also makes obstacles harder to get over approaching a rock fully inflated your tires first action is to bounce off the rock. The same rock aired down like Huey said the tire will actually conform to the rock and you just crawl right over. I to was concerned about ground clearance and was the reason why I did not want to air down but really how much can we be loosing. All the guys I went with aired down to 16PSI and they had no issues. I have never had to air down at the beach yet even though I see people stuck all the time including my bro's wrangler following me but If I ever do get stuck on the sand I would air down 20PSI and drive away. So for sand mud feel it out I guess but rocks and stuff I would air down.