TST TPMS Systems

[Dunner]

A little tip that may pertain to some. If you remove your sensors during the off season, either put cheap plastic caps on the valve stems, or "burp" or "pop" the valve cores before replacing the sensors. A tiny bit of dirt could plug up a sensor and either make it in-operable or give false readings. Tire covers may help, but I would still burp them before adding, checking air pressure or replacing the sensors.

[washbob]

Purchased the 507 system with eight flow through sensors and four regular sensors for my toad while at the Good Sam Rally. Installed them today and I'm not receiving accurate PSI readings. For example my steering axle tires are inflated at 110 psi (verified with two different gauges), but the sensors are reading 104 psi for both tires. I have similar results with my duals and tag. The readings are between 4 and 6 psi off from my gauge readings. As for the toad, it's a little better but the best result is 3 psi off. Called TST office for advice. The first phone call, I was told to switch the sensors around and see if I get the same readings (?). The second phone call I was told that pressure gauges are usually off by +- 2 psi and the sensors are off by the same amount, so 4 psi off would be normal. I informed them that I was as much as 6 psi off. It was then recommended that I check the valve core and try backing it off. I tried that and the readings have stayed the same. I had a previously installed TPMS (pressure pro) that I'm replacing with the TST and I had correct psi readings as compared to my gauge. Was wondering if anyone has experienced this problem and have any recommendations for a fix.

[TST Systems]

Originally Posted by washbob

Purchased the 507 system with eight flow through sensors and four regular sensors for my toad while at the Good Sam Rally. Installed them today and I'm not receiving accurate PSI readings. For example my steering axle tires are inflated at 110 psi (verified with two different gauges), but the sensors are reading 104 psi for both tires. I have similar results with my duals and tag. The readings are between 4 and 6 psi off from my gauge readings. As for the toad, it's a little better but the best result is 3 psi off. Called TST office for advice. The first phone call, I was told to switch the sensors around and see if I get the same readings (?). The second phone call I was told that pressure gauges are usually off by +- 2 psi and the sensors are off by the same amount, so 4 psi off would be normal. I informed them that I was as much as 6 psi off. It was then recommended that I check the valve core and try backing it off. I tried that and the readings have stayed the same. I had a previously installed TPMS (pressure pro) that I'm replacing with the TST and I had correct psi readings as compared to my gauge. Was wondering if anyone has experienced this problem and have any recommendations for a fix.

Sir,

We have six different gauges ranging from stick gauges to very expensive digital gauges.

Every single one of the gauges we use came with an accuracy disclaimer professing accuracy within +/- 2 PSI.

The variances between the gauges themselves vary up to six PSI on the same tire, within our warehouse, completely unaffected by outside stimuli such as heat, sun, etc.

If your shrader valve stems are not straight, this could cause a slight skew in your readings.

Our system is accurate within 1.5 PSI, so knowing what I do about gauges, if your gauge and your system are within about 4 PSI of each other, this is an acceptable varience.

You also might try tightening your sensors another revolution as they simply may not be fully depressing the shrader valve which will also cause a skew in your readings.

I will be happy to discuss this matter further with you. Just give me a call at your convenience.

Thank you!

Dan Covington
TST
(770) 889-9102

[greystroke]

Just remember your standard guages should have an accurracy ratio of 4-1 when possible. In other words, if your trying to prove an accuracy or 1.5 psi your standard guage should have an accurracy of .375 psi for the range you wish to calibrate. The standard should also have a traceable calibration to NIST.

What I look for on my system is repeatability. Once I know what the value is I don't care if the accuracy is a little off as long as I know since I check my tires with a regular guage. Then I monitor for changes. My front sensors differ by about 4-5 psi. My back tires are pretty much together.

Maintaining an accurracy of 1.5 psi throughout the whole range of pressure is probably not going to happen. Again as long as I get repeatable repeatable readings at a given pressure, I am satisfied.

[Half Dimes]

Originally Posted by greystroke

...
What I look for on my system is repeatability. Once I know what the value is I don't care if the accuracy is a little off as long as I know since I check my tires with a regular guage. Then I monitor for changes. My front sensors differ by about 4-5 psi. My back tires are pretty much together.

Maintaining an accurracy of 1.5 psi throughout the whole range of pressure is probably not going to happen. Again as long as I get repeatable repeatable readings at a given pressure, I am satisfied.

That's the way I look at it, too. Before installing or reinstalling the sensors, I air the tires up to where they should be using what I consider to be a reliable gauge. When I put the sensors on, I usually see a variance of +/- 1 or 2 lbs from what the gauge said. At that point I don't really care as long as I have established a baseline.

I think in this digital age, we begin to expect 100% accuracy in digital displays forgetting that some mechanical process or other variable is involved behind the scenes whether measuring air pressure, electrical voltage, or even body weight. And we all know those digital bathroom scales always read too high.

[Sky_Boss]

Dan,

I will later on post my experiences with your company. In short...you and your folks do a damn good job making folks like me happy. TYVM!

I have the external sensors now and all are up and running. The other day the ambient temps were middle 80s. I got out on the road that day and put on about 20 miles at 60 mph or so. I was a bit surprised that I didn't see any of my tires get above 100* and they were all pretty close to a band of 95* to 100*. I am running a slightly higher pressure than needed but only about 3-5 PSI extra for the weight of my coach. Tires are brand new Michelin 235/80/22.5 if that is any factor.

For you or anyone else, would that be fairly normal? I was just thinking I would see more than 15* above ambient temps.

BTW, would you recap your thoughts on the use of any thread preps to avoid seizing to ease removal when needed? THANKS!

[washbob]

I can live with the psi difference readings. I aired all the tires up, checking with an expensive digital gauge and an older calibrated gauge before installing the sensors. I will factor in the monitor reading versus my initial air reading and proceed down the road with that understanding. I was curious how all tire readings (12 tires) ran from 3 psi off to 6 psi off. Technically all the tires should be off pretty close the same if I was using the same two gauges to verify prior to installing. I'm pretty snugged on with each sensor, but it's possible that one sensor is on tighter than the other and the valve core's could be different. Again I can live with that as long as I have a base setting to operate and I do now. Heading out this weekend for a ten day trip, so I will give the system a shake down cruise. I wasn't bad mouthing the system in my initial post, just curious about the readings. I definitely like this system better than my old pressure pro system. I was consistently dropping tire readings (even with repeater) and sending sensors back for battery replacements I specifically went with this system so I could replace sensor batteries myself and I like seeing tire pressure and temperature on the same screen. I purchased a repeater with the TST system and I was getting readings on the monitor in my home office when the motorhome was parked 100 feet away inside my closed RV garage. That impressed me.

[Dunner]

Don, when I go to play in the sand near Yuma, the ambient temp is usually below 75° when I head that way. If I recall correctly, my temps are usually in the 120° range or lower.

[TST Systems]

Happy 4th of July everybody! THANK YOU to our veterans for your time and sacrifice so that we may enjoy our nation's birthday!

Dan Covington
TST

[SpringerPop]

Long post, but it may save someone from experiencing the same grief I went through a couple of months ago when the system first arrived. I wrote the following on another forum on May 22nd, but just found this thread. After reading the entire thing, I find that this issue has not been addressed, so here goes:
--------------

May 22, 2012:
The 507 finally arrived this afternoon, which allowed me to take the sensors to my tire guy, who could now balance my new Maxxis tires.

Brought them all home and decided to activate the system. The YouTube videos were almost more helpful than the written instructions, and I had all the sensors "paired" with the display with no problems at all.

However, after ensuring that all the tires were at the same pressure, and setting the upper and lower limits, I couldn't get two of them to display anything at all. The other two worked "as advertised".

After noting that the two that worked had released "just a bit" of air prior to the gaskets sealing, and the other two non-operational ones did not, I determined that those two were not depressing the Schrader valve.

Hmmmm. I loosened the valve out to the point that there was air leaking past it a bit, and screwed the sensor back on. That resulted in the air just continuing to leak when the sensor was tight! What 'da heck????

I finally determined that any of the sensors would work on the two stems that worked initially, and none of the sensors would work on the two stems that were dead initially. Now I was getting somewhere!

I'm a tool junkie, so I have the tool to chase the threads on a valve stem. One of the functions is a thread "die" for the outside of the stem. If anyone's interested in trivia, it's a 0.307 x 32 thread. (How's that for an obscure size?) The tool looks like this:


I have determined tonight that my tire guy uses cheap (where do you THINK they were made?) metal valve stems. The O.D. threads WERE NOT THREADED FAR ENOUGH (and were slightly tapered), and the TST precision-made sensors wouldn't screw far enough on to depress the Schrader valve. After using the die to correct the errant Oriental threading job, the entire system is now playing a "right-nice tune".

I'm going to let it play overnight to see if there are any slow leaks.

Tomorrow, I'm taking my two spare tires to him to break apart, install metal stems, and balance.

I'm also taking that die with me, and before they go into my spares, those new stems are getting properly sized. I don't wish to re-discover this problem on the road somewhere!

Hopefully this helps someone, somewhere......

Pop

[SpringerPop]

I'd like to add that the initial outing for my -507's was about 200 miles, and we were gone for five days.

The system played absolutely flawlessly!

As a side note:

On the return trip, half-way down Cajon Pass (above San Bernardino, CA), I saw another in our "party" stopped at the side of the road, so I pulled over. He told me he THOUGHT he'd seen some smoke, and was investigating. I pulled out the IR thermometer and shot his six trailer hubs and tires, the four on his truck, and his differential cover. All were normal temps, and all were OK to the touch.

He admitted that he might have been "seeing things", and I followed him to the bottom to his turnoff. He later called to tell me he had made it back to San Pedro without incident.

I got to thinking about the whole thing, and here are my thoughts:

I'm driving along with a fair degree of confidence in the "health" of my trailer tires.

He's taking his eyes off the road ahead to "monitor" his fifth-wheel's tires in his mirrors.

He's now made it to the side of the road while eighteen-wheelers are whizzing by mere feet away

I, too, had to make an unnecessary roadside stop to lend assistance.

We both needed to merge safely back into downhill truck traffic to be on our way again.

He still had to keep monitoring his mirrors after I stopped trailing him.

There's more than just peace-of-mind involved here. It's a safety issue! I'm a believer!

Right now, the trailer is in my driveway, and the display monitor is plugged into a 12-volt outlet inside. Every time I crawl inside to take on another "project" (did I mention it's a '99?), I take a gander at the display for enough time for all four to cycle through. Though they vary only a couple of PSI depending on time of day, the pressures are always slightly higher on the sunny side.

Pop

[Dunner]

I had a tool like that for many, many years. It somehow grew legs and I can't find it. I hate when I lose a tool.

Even with my 507, I still check my trailer tires in the mirrors. Habit I got into when I had a 5er with ST rated tires.

[sdennislee]

Originally Posted by SpringerPop

Long post, but it may save someone from experiencing the same grief I went through a couple of months ago when the system first arrived. I wrote the following on another forum on May 22nd, but just found this thread. After reading the entire thing, I find that this issue has not been addressed, so here goes:
--------------

May 22, 2012:
The 507 finally arrived this afternoon, which allowed me to take the sensors to my tire guy, who could now balance my new Maxxis tires.

Brought them all home and decided to activate the system. The YouTube videos were almost more helpful than the written instructions, and I had all the sensors "paired" with the display with no problems at all.

However, after ensuring that all the tires were at the same pressure, and setting the upper and lower limits, I couldn't get two of them to display anything at all. The other two worked "as advertised".

After noting that the two that worked had released "just a bit" of air prior to the gaskets sealing, and the other two non-operational ones did not, I determined that those two were not depressing the Schrader valve.

Hmmmm. I loosened the valve out to the point that there was air leaking past it a bit, and screwed the sensor back on. That resulted in the air just continuing to leak when the sensor was tight! What 'da heck????

I finally determined that any of the sensors would work on the two stems that worked initially, and none of the sensors would work on the two stems that were dead initially. Now I was getting somewhere!

I'm a tool junkie, so I have the tool to chase the threads on a valve stem. One of the functions is a thread "die" for the outside of the stem. If anyone's interested in trivia, it's a 0.307 x 32 thread. (How's that for an obscure size?) The tool looks like this:


I have determined tonight that my tire guy uses cheap (where do you THINK they were made?) metal valve stems. The O.D. threads WERE NOT THREADED FAR ENOUGH (and were slightly tapered), and the TST precision-made sensors wouldn't screw far enough on to depress the Schrader valve. After using the die to correct the errant Oriental threading job, the entire system is now playing a "right-nice tune".

I'm going to let it play overnight to see if there are any slow leaks.

Tomorrow, I'm taking my two spare tires to him to break apart, install metal stems, and balance.

I'm also taking that die with me, and before they go into my spares, those new stems are getting properly sized. I don't wish to re-discover this problem on the road somewhere!

Hopefully this helps someone, somewhere......

Pop

Good information.

I would have thought about the schrader valve but not the threads.

[SpringerPop]

Originally Posted by sdennislee

I would have thought about the schrader valve but not the threads.

Took me a while to think about the outside threads, too.

Pop