hey gator ...just a thought i had this morning....is it possable that you have 1 or more slow leaks?...so if the psi is right at your house and buy the time you get out on the trails you have lost some air?....especialy? if you loose your bead alot in a mud hole sounds like a good chance for a dirty bead...and slow leak.....if you have them all even at the house and let it sit....any loose air?