tire pressure monitoring system

[turbostar]

Hi Guys, I'm looking for information on the tire pressure monitoring system (tpms). I wish to avoid this complexity if I can. I have been told it started with 2007 models but I have seen the sensors on the net for earlier models also. Anyone know for sure when the Silverados started using this system and how do you tell if your truck has it? I have a 2006 Silverado 1500 and I'm looking at a 2009 1500. If the 2009 has this system and the 2006 does not, then I will avoid the newer truck. TIA