We have the TireMinder TM55c system for the trailer. This model only supports 5 sensors and a max of 80 PSI, so not appropriate for the OP's needs. They do make models like the TM-77-6, which I believe is very similar, that are appropriate though.
TPMS was one of the first must have items for me when we bought the trailer. The TireMinder is the only aftermarket system I'm familiar with, but when it comes time to replace it I will do more research. Overall, I'm happy with it, but there are a few issues, probably common to most, maybe all, of the systems.
We did try the system without the repeater. As far as I could tell, it worked about 80% of the time. The other 20% of the time, it would report signal loss. Adding the repeater fixed that problem. We installed the repeater on the A frame near the tongue of the trailer and tied it to the trailer battery.
So, here are the the issues I see:
- Notice I said "As far as I could tell" about the signal loss above. The literature for the TM-77 indicates that the sensors check the tires every 6 seconds, but the system only updates every 4 minutes. As far as I can tell, the system doesn't have any indication of when updates are received. I assume if there is a problem detected, it will update immediately, but I'm not certain of that. If not, 4 minutes could be a long time to wait for notification of a sudden pressure loss.
- The sensors only transmit, at least regularly, when they detect motion. This conserves battery life. However, we often park the trailer and leave the TM display/receiver in the truck. Some time later we will take the truck to do sight seeing or errands and at some random interval, sometimes hours later, the display will wake up and alarm with loss of signal.
- Turning the display on and off is kind of quirky and not intuitive.
Now the good things:
- Never had a problem with loss of pressure around the screw on sensors
- It's nice to have the temperature of the wheel
- I like that the display has it's own internal battery and I can put it wherever I want without having to worry about wires. Battery life is excellent as well.
