What is the best dash mount tire monitor?

I would just like to respond to a statement made above. I have to disagree that an internal monitor is particularly more accurate than an external monitor. The external monitor measures its temperature directly from the same air that it is reading pressure from so is as accurate as an internal monitor.

I have also had a look at the Dill website and would note that is is restricted to 4 tires so you can only monitor your trailer. It also only alarms at 20% or 30% below set pressure compared to the InnoTechRV system which alarms under several conditions including; slow leak and fast leak, based on the rate of a 3% pressure drop over a period of under 2 mins or between 2-10 mins; three levels of low pressure (15%, 25% and 50% normal); and also high pressure (120% normal). All of these different alarms cater for the many different scenarios that might be causing a a problem with the tire.

External monitors make it much more easy to replace batteries or a faulty sensor and certainly with the InnoTechRV system the sensors are so light as to be extremely unlikely to require a wheel balancing (we have yet to hear of anyone needing one.)

The only way someone is going to steal them is to conveniently have the right size fine Allen wrench on hand. It takes a minute to get one off. So it's not like they'll just walk up quick and spin it off.

It's as safe as your CH751 basement door is. Let's put it that way...</SPAN>

KiwiRVer said:

The external monitor measures its temperature directly from the same air that it is reading pressure from so is as accurate as an internal monitor.

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So you are saying the a dragging brake or hot bearing will show up as well measuring at the stem as appose to the larger volume of air inside the tire. I and most OTR drivers would like to to see the test data that would support that claim. Also the batteries on the Valor internal system will most likely last as long as the tires will (3-5) year because their batteries are the same technology as cardiac pace makers which last 10years. I don't think you can buy those kind of batteries off the shelf for you stem sensors.

I also have a Valor system and went with it for the inside temperature being monitored. Certainly the TST system might have 3% accuracy but it is 3% wagging on the end of a valve stem....in both hot and cold weather. My Valor with its 3% is mounted right where the heat is being generated. I like that a lot better for my investment.

I sell environmental chambers and the competition loves to talk about their +/- .1 sensor (just like my product has) but they don't have the control circuitry to use that accuracy. you look hard at the little print and their temperature swings are in the 3 - 5 degree range while my product is .5 degrees....because it has the matching components to take care of the accuracy of the temperature sensor. So you have to look past how good something is and see how it is being used.....the weakest link always controls accuracy and it is rarely the sensor.

Not doubt TST are good folks and I know they give good service from all the claims on the site when something breaks.

On another thread on this website today there was a great comparison with diesel fuel additives. I would love to see the same kind of shoot off between TPMS systems. But the interesting thing is that when they did the "control"....my guess is they would use the inside of the rim temperature as a control.....not something hanging off of the side of the wheel.

I will say this...it notices the difference between the sunny side and the not so sunny side. I've proven that. It's very quick to respond and seems to show a tire temp difference from a tire thats a few pounds lower on air then the rest.

As far as batteries go, how much is the cost of replacement vs tearing down a rim to replace the others? These are cheap and quick to replace. You can buy them everywhere also. No worries there. Do the math...i'm guessing its a wash.

dave10a said:

So you are saying the a dragging brake or hot bearing will show up as well measuring at the stem as appose to the larger volume of air inside the tire.....

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A dragging brake or hot bearing will have the same effect on the temperature of the air inside the tire regardless of what sensors you are using. Air inside a tire is heated partially by its own movement within the tire (molecular boundary friction between the air and rubber) but more from the actual heating of the tire rubber itself (conduction) which is caused by friction with the ground. This friction increases if the tire is being restricted from turning by a dragging bearing or brake (or due to distortion caused by factors such as tread separation, for example). External TPMS sensors open the valve so that it is constantly measuring the actual air pressure and temperature from the air that is circulating inside the tire, it does not directly measure the temperature of the stem itself or of the tire rubber.

Whilst I don't have scientific data, I would say that common sense and some basic university physics from 30 years ago leads me to believe that there is unlikely to be any significant difference in temperature between the air that fills the greater volume of the tire and the air that fills the inch or so of the valve stem as the air inside the tire is constantly circulating as well as oscillating up and down the tire stem due rotation and to the effect of the "flat" spot on the bottom of the tire.

So the suggestion is that 1/2 degree error sensors are worth the added expense over 3% error...then you have way more money that me. Knock yerself out, but realistically to put it into perspective...you're talking about 2-3psi and maybe 5 degrees at most.

gpshemi said:

So the suggestion is that 1/2 degree error sensors are worth the added expense over 3% error...then you have way more money that me. Knock yerself out, but realistically to put it into perspective...you're talking about 2-3psi and maybe 5 degrees at most.

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You missed my point. It is not only the accuracy of a sensor that counts but how that accuracy is "used" that is important.

And to your comment about "only 2 - 3 PSI". When I did my investigation into tires I was told by Tread-it that with a 5 PSI drop in pressure a tire loses 200 pounds of carrying capacity. For me that is 800 pounds so it is important! And it seems that especially with the standard tires our rigs run very close to the limit. And, of course, that is why so many of us have upgraded.

Sorry. I didn’t miss your point at all. I just think it’s unreasonable. What you’re arguing is the additional sensory accuracy is needed. I get it. I just don’t agree with you that the additional accuracy is needed given real world conditions.
<O</O
<O</OI won’t argue with your logic behind 5psi->200lbs. That’s very likely true. However, I’ll point out though that is more than the margin at which you’d know you have a change with a 3% error giving a 2-3psi change. Right? That’s a good thing. Pull over if you don’t like that change. I still think it’s extremely reasonable though, but more over REALISTIC. I see that kind of difference in just tire temp and pressure increases from the sun - side to side - while parked. It doesn’t indicate a problem, it indicates a change you can monitor. You’re not running your rig within a 3% margin of safety I’m sure of that.
<O</O
The reason we change tires over isn’t what you stated, it’s that ST tires are mostly china junk not worth the ratings.<O</O

3% 5% .5%??????

How many are actually using a tire pressure gauge that can measure accurately?

I got my TST 510 system at the Nashville Rally. Worked well except I had a set of sensors that were made wrong and corroded onto my valve stems. Seems I was one of a very few set of customers.
No questions asked and when all the sensors were replaced the TPMS for the 507 system.

I have no problem changing the batteries yearly, because I can. I would have a problem breaking down my tires every three years for batteries because it is something I cannot do myself.

The 507 suits me fine and it just saved me again yesterday afternoon on the Ohio Turnpike.

We're on the same page. I don't think you can porthole. You're right. I ended up filling and letting out a little at a time to get mine all my sensors to read the same. A little anal perhaps, but it was easy enough to do. Bottom line is stem sensors work great if you've actually ever used them. Realistically they're all good units I'm sure.

As a side note, I had an enternal sensor in my wifes van go bad, and the tire kept going low over the course of a week. Took two different tire removals (two trips and my time) to figure out what was going on, and get new seals for it.
With an external sensor...you could just take it off. Just remembered that mess...