How do you add air to trailer tires without air inlet ports?

it's a closed system, you can't stick a tire guage to it.

without disassembling it.

 

Attached

 

You would have to disconnect each air line in turn and check the tire with a gauge. And yes, of course each tire does have a valve stem. You just need to look harder.

The tire inflation system will keep the tires aired up to a set pressure so why do you need to mess with them? If you're just looking for reassurance then you could buy a TPMS and insert a transponder between each valve stem and each inflator line. Just a waste of money if you ask me though.

 

if it's company truck, they may frown on taking all that apart.

 

It’s no harder than unscrewing a stem cap. It’s meant to be done. I’m not even sure it takes a single second longer. I can check all trailer tires in 3 minutes or less. I got out of my sleeper while we are chatting here to show how easy and quick. But to each their own. I’d rather check psi every now and then rather that blow a tire.

 

Auto inflation system. It will inflate by itself and you don't have to worry about it much. Just thump them to make sure they're inflated. Only time I had low one when it caught nail and was able to drive to nearest service station.

 

They make systems with external valve stems.

 

The "center pin" is describing the pin in the center of your pigtail from truck to trailer. The center pin wire should be blue. This is the circuit the ABS system uses for power.
My trailer blue wire powers the ABS and the auto inflate system.
The white light for the auto inflate system needs to be tested once in a while. The tires could be losing air and the white light could be burned out and may not come on.

 

That’s the way to go. My next trailer will definitely have an auto inflation system. No auto slider. Had one on my last trailer. More trouble than it’s worth.