At the border, entering the "country" of Transnistria. Photo taken December 8, 2016.
Where are Kevin and Ruth right now? Tiraspol, Transnistria...the country that doesn't exist.

Where are they going next? Northern Moldova. Arrive December 11th.

Friday, May 6, 2016

A neat product, but...

As wireless technology continues to improve, manufacturers are coming out with some innovative products. Over the last couple of years, one of the neat things is wireless tire pressure monitoring systems.

I'm a stickler for checking my tire pressure, both on the motorhome and the car. It's important to have the proper tire pressure, and I learned from my years in the automotive business that many people don't check their tire pressure often enough. With the proper pressure, your tires last longer, you get better gas mileage and ride quality, and it's safer.

A couple of weeks ago, I received a small package. Here's what was inside the box...


  • Four sending units
  • One display module with USB port
  • Small tool kit
  • Intructions
  • Warranty card
I waited until we got back to Cabri, and I installed the sending units on the little blue car. Simply remove the valve stem cap, spin on a little lock nut, screw the sending unit on to the valve stem, and tighten up the lock nut. Simple.

Then, plug the display unit into your cigarette lighter power outlet.

Within 30 seconds, the display unit had read the signals coming from each tire.

But there's a problem.

The car had been sitting all winter and I had just topped up the tires to the recommended 30 psi pressure. Yet the sending unit was telling me there was only 28 psi in each tire. I removed one of the sending units and double checked the pressure with the guage that I keep in the motorhome. Yep, 30 psi. I then triple checked with a guage that I have in the shop. Yep, 30 psi.

So that's the first problem, the sending units aren't accurate.

The display unit has high and low settings that give you warning if the tire pressure starts to drop. I set the low at 24 psi and the high at 36 psi. It also gives temperature readings (in Celcius only) of each tire, and you set parameters there as well.

Then, we drove into Swift Current and back, a total distance of about 140 kms (87 miles) return.

As the tires warmed up, the readings went up to about 32 psi. This is normal, but they were still reading lower than what they should be. When we returned home, one of the tires had dropped down to 29 psi and I figured out that I simply didn't have that sending unit tight enough on the valve stem so it was slowly leaking. Hey, at least it was telling me there was a problem!

Everything went fine....except for one thing.

The sending units are actually fairly heavy for their size. And the valve stems are only rubber. So what happens is that the centrifugal force of the spinning tire causes the valve stem to bend outwards, and in the case of the little blue car this causes the wheel cover to actually cut into the rubber valve stem.

Notice the gap between the valve stem and the silver wheel cover.

When the wheel is spinning, the valve stem presses into the edge of the wheel cover. You can actually see in the first photo where it has slightly cut into the valve stem.

The display unit.

So, because of the valve stem problem, this won't work in the little blue car. In order to make it work, I would have to replace all of the valve stems with metal ones such as these...


So, you could make it work if you want to. Instead, I'm going to try it out on the motorhome. I'll install all four sending units on the rear wheels so at least I can monitor the duallies. I tried out the one furthest away, and the distance still works with the sending unit plugged into the dash of the motorhome. Plus, the motorhome already has steel valve stems.

I don't like the fact that the numbers are off by a couple of pounds, but if it's across the board and you know it then it's not that big of a deal. I mean the whole idea is that it warns you when it's going down. And, possibly it's just this unit that's slightly defective, although given that all four read a couple of pounds low, I doubt it.


For $90, I think it's probably priced right, but better quality systems are available at higher prices. And, you can get systems that specifically come with six sending units for use on vehicles with more than four tires. 



16 comments:

  1. Nice critique on the pressure monitoring system :-)

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  2. I saw the shoirte rpost on facebook. Yes you shoudl alsways change out to metal stems, I foudn th echeaper unit sliekthis are pretty much a waste of money. You relaly need to spend about $500 on soemthign like http://www.tpms.ca/

    I went the $100 route first and ended up throwing it out. In my case its especially importnat to have a good quality system that also measures temperture as i tow a trailer. Sensors are $50 a piece with the better system.

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    Replies
    1. I would agree that it is especially important when towing a trailer.

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  3. We bought an expensive unit & put it on our other motorhome. All 6 stems leaked air. Not fun in a motorhome. Got rid of it.

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    1. I'm surprised that an expensive unit had that problem. They obviously haven't perfected them enough to be reliable.

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  4. I know a lot of people who had spent the big bucks on the expensive ones and most have had problems with them. Myself like you check the tires especially on our coach, each time before we are on the road. Not a big deal for me.

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    Replies
    1. Right, not a big deal for me either. But the whole idea behind a system like this is not to let you know what the tire pressure is when you set out. It's to let you know if you have a problem while going down the road.

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  5. The centripetal force on the valve stems is significant---several POUNDS in fact. I bought a $250 four-sensor TireTraker system a few years back and had to upgrade to "high pressure" stems (not metal ones) but after having a rear trailer tire almost destroy itself, the peace of mind a TPMS provides is priceless. My sensors also report about 2psi low, but I don't lose sleep over it.

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    Replies
    1. I think I agree...it wouldbe most useful to have the system on a trailer or fifth wheel.

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  6. I'm with you and am a stickler for checking my tire pressures. I chose not to have a monitoring system after reading and hearing of many people having real problems with them.

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    Replies
    1. Yep, it seems the haven't made them reliable enough yet.

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  7. We purchased an EEZ RV TPMS and so far have had very good results.

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    Replies
    1. Well certainly if price is any indication, yours is a much higher quality unit. Glad it's working out for you.

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  8. Catching up on some of your past posts. The working pressure for the units only go to approximately 87 PSI, thus good luck on using them on your MH. *smile*

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    Replies
    1. The motorhome's tire pressure is 60 psi.

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