When should red trailer valve pop out?

Nope…

Driving down the road bobtail (without a trailer attached) the trailer valve is closed. Do not push it in or you will lose your air pressure. In 21 years and many DOT stops, I’ve never seen or had anyone tell me to push the trailer knob in while bobtailing.

 

Yes, That's the ways It's supposed to work..!!

 

I think theres a technicality that hes correct, such that if operating with a trailer, and the red line snaps, the red valve is supposed to pop itself out after a bit (as he said tractor protection valve) but unless i miss my guess, its to do with air flow (cfm delivery) over the tractor protection valve, not a specific psi (i may be wrong) that being said, my truck won't let me release trailer brakes under about 55 +/- 10 psi

As you say though, you never push the red one if you dont have a trailer

 

Strike a nerve did I Genius ???
Sorry to disappoint you but I've driven for myself for 34 yrs ... I know when or when not the trailer valve should be in or out.. it's not rocket science

 

I know how a air brake system works
It's obviously you don't..
You suppose to know how things work if your driving it ..
People like you scary me.. and I don't scare easy

 

So how long you owned your own truck??? And how long have you been driving trucks with air brakes???