I'll tell you a story...
I was pulling our 30' Keystone OUTBACK Superlite 5th Wheel...and I noticed the vehicle taking a little extra pedal to maintain 65mph... Nothing else. A few minutes later...a very nice lady pulled up along side me. Rolled her passenger side window down...to which I rolled down my drivers side window in reply. She asked "Do you know your tire is busted?"
Dangit. Now the extra pedal makes sense. The left rear tire on the 5th wheel had blown...and wrapped itself all in everything. I probably would have noticed when the left front one went. Luckily, the nice lady acted as my Tire Monitor.
I purchased a system right after that. I have used it ever since.
In addition to notifying you of a blown tire...if you're like me and fail to recognize it... the TPMS will show you the tire pressure and temperature. This really saves you time in the morning. I used to drag the gauge around and check all the tires. It was a lot of bending over and...well, not so bad with four tires on the fifth wheel. Now, with a Class A...pulling a Jeep...that's 12 tires to check. The TPMS does it for me. I have coffee...wait for all the sensors to answer role call...and sit at the helm, and check tire pressures from the comfort of the coach.
I think they are an invaluable tool...which may reduce damage to your TOAD or RV, by giving you an IN YOUR FACE wakeup call to the fact that a tire is HOT, LOW ON AIR, OVERINFLATED, HAS A SLOW LEAK, or BLOWOUT.
They all do about the same thing. Relay pressure and temperature to a display...which is programmed to the parameters of your choosing. I will say...If I purchased one today...knowing what I know now...
1) How is the Alarm displayed? In plain text? or some hieroglyphic symbol that you won't remember six months from now? Honestly, the little hieroglyphs all look the same when the Horn is beeping at you.
2) Do the sensors accept user replaceable batteries. I change mine every year. It's an extra glance at the health of your valve stems, and the weather resistant 0-ring. I actually found a leaky coin battery this year. First time for that. Sensors are expensive...and you want them to last as long as possible.
3) This is, evidently, a minor issue. The maker of my tire monitor says NOBODY has a problem with this...and they have thousands and thousand in use. I had a situation where after adding air to a tire...I replaced the sensor. The display showed 0 PSI. I know the tire had pressure. I pulled the sensor off and looked at the inside. There is a device called a Quill Depressor. It is what engages the "quill" on the stem valve...to allow air out of the tire and into the sensor body. The manufacturer of mine had made these Quill Depressors out of plastic. I thought that odd. The plastic had splayed...and was no longer pushing down the quill. I queried the company as to why this was plastic and not brass...and was told...they cannot use brass as there would be dissimilar metal galvanic corrosion...and that it was my fault for having over tightened the sensor, or not having the valve stem depth set appropriately. Take that as you may. Their sensor already has brass on the outer threaded portion. Their more expensive sensors for OTR truckers has a brass quill depressor. Many other brands have a brass quill depressor. Secondly, the depth of my valve stem isn't something you decide. It is generally where the valve stem stops when you tighten it to 3.4 to 4 in-lbs of force. And finally, which would you rather wear out? ...a ten cent valve core? or a $50 sensor? I would rather a robust sensor...at the detriment of the valve core should I supposedly over tighten the sensor when installing. That's just me...buy what you want. Evidently...I'm the only person to ever have an issue with a plastic quill depressor. I was told I could purchase FLOW THRU sensors and simply remove the valve core from the tire stem. Yeah...still not giving me a warm fuzzy.
Back to the theme. YES, YES, YES...they are very worth having.