I think you guys are confusing off-roading vehicular drive systems with an idling wheel dolly. When driving wheels (i.e. from a drive train) over inconsistent and soft ground, it will keep them from digging in and getting stuck if the tire is deflated quite a bit - more contact area spreads out the loads and keeps it from burrowing under power. However, for an idler wheel like on a cat dolly, my experience is that more pressure is always better as you loose a LOT of energy when the tire is squishing in (ever notice how hot a tire gets when run with low pressure - that's the result of a loss of energy...i.e. extra energy required to get it to roll).