The max is the pressure to use, 50. And it should be kept at that pressure. I believe the 32 is the max pressure to use when seating the bead. Even on TireRacks site, in the information section, it states never exceed 40psi when seating the beads, this for any tire.
http://www.discounttire.com/dtcs/inf...rTireFacts.dos
http://www.tirerack.com/tires/tirete....jsp?techid=20