Tire Monitor

[huffypuff]

I attended a tire seminar in Redmond. OR this year and I remember it being stressed to get a tire pressure monitor for the coach and toad. I did so before leaving the reunion and was quite disturbed by the operation of them.

These have sensors that screws on the end of the valve stems and transmit to a receiver kept in the coach. I didn't have the toad with me at the time so I only installed the sensors on the coach. Tire are Michelin 275/70R22.5 XZA2 Energy with about 7,000 miles on them and less than a year old.

The first thing I noticed is that reading from all the senors on the monitor itself is reading 5 lbs too high. I verified it with two known good tire gauges. The second thing I noticed is the temperature started out normal but didn't raise much while driving. When I stopped at a rest stop in Washington then the temperature raised about 10 degrees in about five minutes. I wonder how in the world are these sensors supposed to get internal tire temperature if it is spinning around on the stem on the outside of the rim?

Maybe there should be a seminar on tire monitors so it could be explained what a misfit add on are. Nothing like the tire monitors that comes with the vehicles today. Hopefully for me it's not $410.00 wasted. TireMinder monitor, charger, 10 sensors, booster and 10 extra batteries.

http://www.minderresearch.com/tireminder/tireminder-tpms-with-6-sensors-and-a-signal-booster-tmg400c-6/

[wolfe10]

Ray,

While I have a different TPMS, let me put this in a little different perspective:

Like an engine temperature gauge, I care less what the absolute reading is as long as I can (1) calibrate it with IR gun and (2) KNOW when the needle moves from that position if actual engine temperature changes. That is really all I want to know-- that the thermostatically controlled temperature is correct AND that I will know if it is not at that reading.

OK, scroll forward to TPMS's. If you have verified the actual pressure with a calibrated gauge (again, calibrated gauge, as they can be off as well), I would not be too concerned that the TPMS is different by a few PSI. This assumes that PSI readings increased as you drove (as it would if you checked with a gauge).

Many TPMS's do not give temperature, as temperature is 100% related to PSI (ideal gas law-- PV=nRT). Said another way, if you know/monitor PSI, temperature is not really relevant.

So, if you have verified that you have the correct PSI in the tires (calibrated gauge) and that the TPMS readings change as they should as you drive (verify with your gauge) it may be doing everything you really need done.

Would you like it more accurate-- probably, but it may be doing everything it needs to to keep you driving on safely inflated tires.

Brett

[tbutler]

When I install new sensors I note the difference between the tire gauge and each of the sensor readings. At 100+ pressures, most are within 1 or 2 PSI but as Brett has said, once that is noted then I know what the readings should be and I will know when I'm getting readings which should cause concern. My sensors don't provide temperature data. A temperature data sensor would have to be inside the tire as you mention. Putting a sensor inside a tire makes it very inconvenient to service or replace so I wouldn't use such a system.

[huffypuff]

Yes the tire pressure did raise about 5 lbs while driving but the sensors or monitor was reading 5 lbs high when cold. They claim accuracy within 2.7%. That means that at 120 PSI it should be no higher than 123.24 psi or no lower than 116.76 psi. The tire gauges has been tested against factory tire monitor system such as my 2012 Cadillac SRX. On many cars you can bring the tire pressure reading on the dash and even watch it change while driving with a touch on a button. True many don't have temperature readings but that was one of their selling points that temperature increase before a blowout. Why sell something with a feature that don't work?

I am disappointed with the performance of the tire minders and think others should be warned that they are not what you may think they are. I'm going to contact the factory and see if they have an answer to my concerns. I will let all know the response.

[desertdeals69]

I use Tire Minder on my coach and toad. Although the pressures don't agree with my gauges neither do my gauges agree with each other! Like Brett says, just be aware of the changes.

[wigginsjsr]

I use a TPMS on my coach and toad. I feel it gives me an additional level of confidence that all is well. I use a separate gauge to fill my tires, and the sensors may vary by 1 to 2 psi. To me the primary purpose is to see pressure changes in relation to where the sensor was originally set. I'm looking out for the dangers related with low pressure. As to the temperature, again the readings are relative to each other. If one tire is getting out of range with the others then I likely have a problem. I have no expectation of exact readings for either psi or temperature.

[jgallego]

It tells you in the book that it might be off a few pounds. I have mine set at 95 psi by the guage but show up around 91 and 92 psi sensors.

[elkhartjim]

I purchased the TST system prior to our trip. We've been 6472 miles and we're still 155 miles from home. I've turned the system off. TST has good customer service but their product has been unbelievable bad. They have sent me sensors on three different occasions, two monitors and I'm still having issues. On my Jeep toad they worked for several weeks and now I will be driving and its like a wheel fell off. No pressure, no nothing. A few miles later it magically reattaches I guess because it starts monitoring again. At least I don't lose the same wheel all the time, it alternates wheels. The motorhome is another situation altogether. One of the faulty sensors magically started working before I received the replacement but thankfully I had the replacement because a different sensor quit working. Another of the replacement sensors worked for several days and now it reads 26# until it decides to read 88# (correct pressure) but then drop back to 45#. I've not had this much worry over tires in the 25 years I've rved. I've checked the air so many times with the guage that every 2-3 weeks I add air because I always lose some air when I check. The sensors are off by 2-9#'s. I can live with that because I will monitor any sudden drop in pressure. As for as temp goes, when we were in Glacier and it was cold, the tire temp was cold...duh. When we were back in Texas the temp was much warmer...Duh! As far as I'm concerned, thats just a sales gimmick. How in the dickens can an external sensor sense tire temperature? It senses the ambient at best.

Rant over except I intend to have a long conversation with TST after we get home. Nobody should need to stop and check tire pressure 4-6 times a day because of a stupid buzzer and a flashing red light.

BTW Huffy, I spent a bunch more than you did.

[huffypuff]

Wow Jim, sounds like my issues are far less than yours. When I check today temperature and pressure on left rear inner tire is stuck at 112 psi and 89 degrees I'm betting that sensor is bad. I haven't driven it in three weeks and it never came down. Well I decided to pull all the sensor, swap bad one for one for toad. Reset unit for reprogram, install booster since I need for the toad later and reprogram after inflating tires with good tire gauge. Once I get the coach working then I have to get the toad ready. I think I have to swap out the sensor for the toad because of factory monitor may have aluminum stems. I'm still waiting for email from tireminder before going ahead with it.

An email from tireman9 explained why the temperature raised when stopped since not internal tire temperature. Coming to the rest stop using the brakes caused it to heat up enough for the sensors to pick it up. That really explained what happen there.

I also have other things to worry about as if I didn't have enough to do I'm upgrading the TV's. Two high tech smart TV's, one 32' for the bedroom and 40' in the front. Want to get them done before a chapter rally coming on the 25th.

[kaypsmith]

WOW, glad still use billy stick!

[huffypuff]

WOW, glad still use billy stick!

Yes I think that is the old trucker way, walk around at every stop and hit it with a stick, If it sounds good your on your way. If I have as much trouble as Jim with mine I believe I will be boxing them and putting them in the rear compartment. This so far gives me more worries when I drive and should leave it alone unless a alarm goes off.

[huffypuff]

I received an answer from the maker of the tire minder and it is as following:

Mr. Huffman,

Thank you for contacting Minder Research regarding your TireMinder TMG400C system.

The issue your are having with the transmitters reading are explained by the fact that most gauges have an accuracy level of +- 1-2 PSI. When combined with the 2.7% accuracy of the TireMinder transmitter could certainly give a pressure reading of 5 PSI difference than another tire gauge when pressures reach over 100 PSI.

The TireMinder transmitter will find the internal tire temperature by the internal air or nitrogen that rests inside the diaphragm of the transmitter. By measuring the temperature of the internal air, we are able to receive an accurate reading within +- 5° F. If the temperature goes to 167° F or above, the monitor will immediately alert the user to check the tire.

To address your last post, please keep in mind that once the monitor is turned on or awaken from sleep, it will take up to 20 minutes for the device to register all new readings. Until that process has completed, the monitor will show the last readings it received from the transmitter.

For a great working system, always remember to use a booster (this will eliminate the possibility of signal interference), change your batteries and O-rings every 9-14 months (if you register the TireMinder system you will get free batteries, caps and O-rings through our battery exchange program), always keep the transmitters at the same position (if adding air, take one off at a time to avoid confusing transmitters) and if you have to change the sensors around, do a full delete by making sure every position in learning mode displays a red light at the top of the monitor.

Please let me know if there is any other questions I may answer for you. Also, you can always contact us here at Minder Research from 9 AM - 4 PM EST Monday - Friday at (772) 463-6522 for immediate support.

Thank you again for taking the time to contact us.

Mike Pescitelli

Chief Technology Officer

Minder Research Inc.

(772) 463-6522

3000 SE Waaler Street

Stuart, FL 34997

www.MinderResearch.com

I have nothing to add at this time except I will reset and start from scratch first installing the booster and the toad sensors after new tires.

[elkhartjim]

I mentioned this in my post and I will reiterate - TST has been very responsive to my needs and not one time have they attempted to deliver some sort of rhetorical corporate nonsense. We are home as of a few hours ago and my next step will be to reprogram my system using a new monitor.

I'm still not convinced how an external sensor be it a TST or any other manufacturer can whirl around in 20 degree temp and read 167 degrees. I'm curious, has anyone had a tire sensor read 50-60 degrees above ambient temperature?

[huffypuff]

Yes the internal temperature on the diaphragm at the end of the stem is different than internal tire temperature. If the temperature raised enough to set off the alarm I would believe pressure would of raised quicker.

[wolfe10]

Ray,

Again, monitoring both PSI and temperature is reasonably redundant. They are absolutely locked together. The ideal gas law from centuries ago (PV=nRT) is "chipped in concrete". A change in temperature of a gas WILL result in an easy to calculate (above equation) change in PSI.

No question-- the temperature at the end of the valve stem is not the same as that inside the tire. But, were you to be able to know the exact temperature of the air in the tire, you would be able to mathematically compare it with the PSI reading and it WOULD be the same.

Sometimes modern electronics provide us with too much information. In my opinion this is one of them.

[huffypuff]

Yes Brett on both points you made.

[tireman9]

Hey guys. I'm still on "vacation" out West. A looong way from Akron, Ohio. In Alberta, Canada. So I don't have access to all my data files on my main computer at home. BUT

Brett's reply is correct. We need to remember the primary purpose of a TPM system is to provide a warning when a tire has suffered a significant pressure loss. The Temperature readings are secondary.

I have done a few posts on my blog on Temperature.

THIS two part post compared IR guns with internal TPMS with a Tire Pyrometer as used in Indy Car racing to learn actual tire temperature. Note No TPM, internal or external will be measuring the actual hottest part of the tire. They can only tell you the temperature of the air contained in the tire air chamber which is always cooler than the tire rubber.

Most TPMS that have temperature warning use 150 to 170F as the warning range. It is very difficult to have the internal air reach those temperatures if the tire is properly loaded and inflated and you are not running at excessive speeds.

HERE is a post on temperature in general.

I would NOT consider a vehicle TPM pressure reading as an accurate reference pressure gauge.

Here is a post showing the real accuracy of gauges used every day by RV owners. If you review the numbers you can see the problem in assuming that an expensive gauge is a guaranty of accuracy.

[huffypuff]

Yes I guess I will be setting the tire pressures with a good hand gauge and let the spinning dabbers be the alarm.

[bizsmith@yahoo.com]

I have TST and have had good performance. While the readings may not be dead on against a manual tire gauge, I feel much safer knowing I will be alerted if there is a tire problem especially on the toad.

[elkhartjim]

The false positive readings have driven me nuts with the TST systems, especially on the toad. When the sensor stops reading from one position and then starts again in 5 -20 minutes and alternates on all four wheels is unnerving to say the least and when I say "stops working", its like the wheel fell off. They may work fine one day and then not the next.

I understand the difference in pressure reading from an accurate gauge but when the sensor indicates 40# when the actual gauge pressure on a rear tire is 85# is not acceptable to me. Once the pressure increases after driving a few miles the sensor pressure may or may not jump to 90-95#.

Like you, Bizsmith, I'm more concerned with the toad having a tire issue.

[rwilli]

Admittedly, I am new to owning a motor coach and confused about the necessity of tire pressure monitors-- seems the monitor reports needed information after-the-fact? I check the pressure on my tires and visually inspect them regularly. What I would find most valuable is a device that can alert me before a flat/blow-out, not after.

[wolfe10]

Actually, the vast, vast majority of tires that fail do not go from perfect to blow-out without loosing air first. Sure it can happen, but most loose air slowly, then really heat up and blow out/throw tread.

That is why I consider a TPMS the same as an engine temperature gauge or oil pressure gauge. All three tell you about a problem and hopefully in time to prevent major damage.

[tbutler]

Two years ago the drivers side outside dual tire blew out taking a sizable portion of the fiberglass on the left rear of the coach. After the tire blew, the tire alarm sounded. There was no indication that the tire was loosing air prior to the blow out. In fact, we had stopped for lunch immediately before this event. I had done my usual walk-around as I do every time we stop. I touch the tires and the hubs to make sure nothing is abnormally hot. We hadn't been back on the road for more than 10 minutes following that stop.

Two years before that we were traveling after dark in Alabama. At some road work we were routed off the road onto the shoulder. I picked up a cargo hook in the right outside dual tire. The alarm sounded and after we cleared the road work I pulled off to investigate. As I stepped out of the coach I heard the air rushing from the tire. Had I not had the tire alarm system I'd have driven on with the full weight of the coach on the remaining tire which being greatly overloaded would have failed quickly. I would have been on rims on the rear axle and nothing good happens after that. So the tire monitors have saved me once which more than pays for the system.

It gives me peace of mind especially with the toad to have some indication of tire problems. The system only works for those occasions when the air escapes slowly from a tire but as Brett said, this is the most common kind of tire failure.

[huffypuff]

OK, finally got around to it as we are preparing for another trip. I installed the booster in the rear bedroom breaker box that also have 12 volt fuses. I then removed all sensors and reset the tire minder and reprogrammed it. I installed all 10 sensor on both the coach and toad. Now the pressure reads within a couple of pounds of what I set it with my long stick gauge. I don't know what went wrong the first time and I'm more happy with this results. We will see how it works on trip to rally starting Thursday.

[tireman9]

The false positive readings have driven me nuts with the TST systems, especially on the toad. When the sensor stops reading from one position and then starts again in 5 -20 minutes and alternates on all four wheels is unnerving to say the least and when I say "stops working", its like the wheel fell off. They may work fine one day and then not the next.

I understand the difference in pressure reading from an accurate gauge but when the sensor indicates 40# when the actual gauge pressure on a rear tire is 85# is not acceptable to me. Once the pressure increases after driving a few miles the sensor pressure may or may not jump to 90-95#.

Like you, Bizsmith, I'm more concerned with the toad having a tire issue.

I can't address specific issues with TST brand as I haven't used them but if you have a position that is providing a reading then it goes off then comes back on I would guess you either have a weak battery or weak signal. Did you get to discuss a signal booster with TST? Is it always the same position? Have you tried a new battery in the problem sensor?

All external systems I know of go to sleep when you stop driving and there is no wheel motion for X number of minutes. They turn on again after Y number of minutes (3 to 10) of motion. Whoever makes the brand of sensor you are using they should be able to tell you the time it takes to "wake-up".your specific system.

Finally RE Temperature

I consider this extraneous information as far as tires are concerned. If you have a pressure loss, yes the temp will increase but the primary purpose for TPMS is to warn about PRESSURE LOSS. Some report having discovered brake drag issues or hub bearing issues with the high temp warning and thats fine, but if your tire has the correct pressure the temperature of an external sensor will be from 10 to 40°F lower than the internal temp of the tire based on my testing.so I would not worry about temperature readings as long as your pressure is OK.

IF you get a high temp reading you can always pull over and see if you can touch the tire, wheel or hub. Don't burn yourself but a quick tap would tell you if you really have a hot tire or a hot hub.