Hello,now on my 2007 F150 I was driving and my tire low pressure lite illuminated.No big thing. Check all pressures Pressure were between 30-35.Anyway went over to my dealer and asked him about it.Tires are low was his reply. Now I had just put 4 Firestone on and they told me 28-35.My dealer showed me on the door for the pressure to be at 38.Whos word do I take? The Ford dealer of the Firestone's tire center?Well I put 38PSI in all tires but the lite still stayed on.Went into the house and had a bite, then came out and started the truck, the light blinked 3 times then went off.Who is right? Thanks Ken

 

Welcome to the site, post some pics. Sounds like a sensor might need replaced, and I would go with whatever the door says.

 

Go with whats on the sidewall of your tire, different tires hold different weights at different pressures.

 

Welcome!