This thread gives the settings to use for both Max and ZBrush when importing and exporting models using these plugins.
IF YOUR MODEL IS IMPORTING INTO ZBRUSH WITH THE UV’S TRIANGULATED, FIRST CHECK TO MAKE SURE THAT “# OF DIGITS” IS SET TO 6 IN THE MAX EXPORT DIALOGUE. IF THAT DOESN’T RESOLVE THE PROBLEM, RESET THE xFORM FOR THE MESH.
ZBrush 3 Threads
Max 8 Tangent Settings for ZMapper (See first post)