What does the "light load" button do on a 2008 dodge ram 2500 diesel with a 6 speed manual transmission?

With this button is illuminated, the TPMS will alarm when the rear tire pressure falls below 45psi. Otherwise, TPMS will alarm when the it falls below 60psi.
Updated on Thursday, February 02 2012 at 10:17AM EST
Collections: dieseldodge ram