For the SoCal off roaders in the house........ I have some very basic front tire questions. At what point are the knobs rounded off enough to necessitate a tire change? My fronts seem to last forever, or at least I can't seem to notice any discernable degradation in traction quality. I'm thinking that maybe it's time to change when all the knobs have lost all of the squared corners. I eat about 3 or 4 rear tires before I change the front. Is this normal, or am I just stupid/cheap/lazy? Now here's a real basic question that I need to ask. I run 18-20 psi on real rocky rides, 12-14 psi on soft (sandy) rides. Is this about average, or am I way off? Lastly, what's a good front tire for SoCal desert running. I know that's a loaded question, cause on any given ride I can be in rocks/hardpack and long sand washes. Opinions?