With the introduction of silica into tire treads in the 1990s, the use of organo-silanes also greatly increased as well in order to achieve the needed improvements in tire rolling resistance.  To effectively use these two compounding ingredients, an in-situ silanization reaction has to be completed before the rubber mix is dumped.  If this silanization reaction was not completed during the mix, the tire rolling resistance and other performance property improvements would not be achieved.  The RPA 2000 has been used extensively to quickly measure the completion of this silanization reaction.  The purpose of this paper is to discuss the optimal RPA test conditions that should be used to determine if this silanization reaction was successfully carried out.  Presented by John Dick, Senior Scientist, Applications, Alpha Technologies.