Tire Pressure Monitors

[H. John Kohl]

You are going to pay the flat rate for the unit(receive) and four tire units. It was $45 for each additional tire unit. So you need a minimum of 8 for both truck and trailer and two more if you monitor you spares too.
They are not difficult to install. Finding a place to mount the receiver display is fun.
PS if you use ham radio you could have an interference problem they use 430 MHz low power.
Good luck and tow safe.