Just to be clear, I didn't say that airing down doesn't work. It most definitely does. But just airing down as a standard practice makes no sense unless the situation is right. Crossing glaciers in Iceland with monster tyres at 5 psi works. Rock crawling with balloons certainly does. Sand driving on slicks may do, but just airing down in a standard off road situation may not actually be helpful. I found that I lost grip. I lost the 'sharpness' of the tyre. The next day fully aired up, I monstered things like the steps at Lincomb where the day before on softies I couldn't get up. Sure sure there are other variables, but having done this a few times in as I said normal off road stuff, harder tyres seems far better. I think that airing down might be as Shayne said, a countermeasure that you might try. But "Ahh we're here, let's let the air out' isn't necessarily the right approach. This is for my tyres, huge great big things that will actually run with no air in. I had a bit of a wobble and checked my pressures and truthfully, one tyre had zero psi in it and I didn't know. Letting the air out does not make it flatten out like a floatation tyre on a tractor.