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Old 04-03-2014, 10:15 PM   #29
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Here's something I've been wondering for quite a while: how do tire minders handle the fluctuation in pressure due to temperature and altitude changes?
I have a VW Touareg that conveniently displays all tire pressures. Starting from home in a cool garage, they can rise by anything up to 6psi on a hot day. And when parked outside, pressure in the tires facing the sun will be way higher than those in the shade.
Do the minders give false alarms?

The TPMS we use on our TV and TT has a fairly sophisticated logic built into it. However certain conditions will cause it to alarm when there is no real problem, but since it is also reading out the tires' temperature and pressure it is easy to identify what is really happening. Here is one example:


Even when driving on a very cold day, the tire will heat from the road friction and the pressure will rise slowly. If we drive at highway speed for an hour or so and then stop on a cold day, the tire may cool quickly enough to fool the TPMS into displaying that the tire has a slow leak, and go into the appropriate alarm condition.


Ken
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Old 04-03-2014, 10:47 PM   #30
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Thank you Tireman9 and Ag&Au. So the consensus is that these monitors should just be used as a guide only, although with time and experience we can get to understand their anomalies.
Peter
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Old 04-03-2014, 11:49 PM   #31
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TPMS an important safety system

I too want to thank Tireman9 and Ag&Au for adding their insights.

Adding a TPMS or not is certainly a personal choice on the Sprinter 3500 since they are not required yet by US law.

I'm convinced they are an important safety system. I'm sure that if I had a TPMS when my inner dual went flat I would have picked up the problem sooner and my have saved the tire. I'm just thankful that the tire didn't blow and then cause the outer tire to fail.
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Old 04-04-2014, 05:56 AM   #32
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I understand what you are implying.
Actually, that's NOT what I was implying. What I meant, and didn't adequately convey, was that TPMS is more important for a trailer than for the vehicle you're driving, because you get less tactile feedback from a trailer than you do from the vehicle that's strapped firmly to your butt.

My opinion is that most drivers— when driving a vehcile they are fully accustomed to driving, at least— are more likely to be able to feel when something's not right with the drivetrain, and they'll have less need to rely upon gauges and idiot lights to tell them what's going on.
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Old 04-04-2014, 10:05 AM   #33
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I have "tire minders" on all 6 wheels. It was a problem getting the rear inside tire minders off and back on with the Alcoa wheels. We bought the AI used (one year 10k miles). At first we got a lot of false alarms with pressure doubling in a give tire then normal 15 min later. We changed all the transmitter batteries and that alleviated the alarms. I also found one xmitter with a broken battery strap and replaced it. On an unrelated issue, one of the inside rear tires was cupped making a lot of noise. We took the AI to Mercedes suspecting a suspension or shock issue. The mechanic quickly noted that we had 5 contis and one Goodrich. The Goodrich was the correct size but not "e" rated. Upon further investigation with the original owner, we learned that he had the minders on the rear inside tires mounted on valve extensions. One of which developed a leak due to the constant motion. He lost pressure and shortly later, the tire. He was 3 hrs from home so he had Tire King replace the tire with one that fit. So we now have 6 contis and tire minders that are reasonably sans false alarms.
Have to wonder if anyone told the previous owner that mixing brands in a dual application is asking for trouble. Duals should be matched by design, type and physical dimensions (OC - +/-3/4") or one tire will be overloaded with the potential for premature failure. See my blog posts on "Duals" for technical details.
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Old 04-04-2014, 10:16 AM   #34
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Actually, that's NOT what I was implying. What I meant, and didn't adequately convey, was that TPMS is more important for a trailer than for the vehicle you're driving, because you get less tactile feedback from a trailer than you do from the vehicle that's strapped firmly to your butt.

My opinion is that most drivers— when driving a vehcile they are fully accustomed to driving, at least— are more likely to be able to feel when something's not right with the drivetrain, and they'll have less need to rely upon gauges and idiot lights to tell them what's going on.



I still don't understand what you are saying in regards to safety.


However my best guess is you are saying some version of:


1. It isn't that big a deal to have a blowout when driving 65 MPH.
2. A driver will do a better job of detecting a slow leak, than a TPMS or at least an adequate job.
3. A driver of a tow vehicle will likely not notice a blowout on the trailer he is towing and that's why they use a TPMS.
4. Gauges and warning lights are only needed by unaware drivers who are not in tune with their vehicle.
5. Or, some combination of the above.


I think I best leave this conversation because we seem to totally disagree on basic philosophy.


I am a safety first kind of a guy, who believes in using every tool reasonably available to avoid a having a problem, or to detect a minor problem before it becomes a major one.


I have an aviation background and the idea that any operator's own senses are adequate to determine what a complicated mechanical and electrical system is doing when safety is a facotr is totally foreign to me.


So lets just agree that we have a different comfort level and risk assessment and abatement philosophy.


Ken
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Old 04-04-2014, 10:17 AM   #35
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Actually, that's NOT what I was implying. What I meant, and didn't adequately convey, was that TPMS is more important for a trailer than for the vehicle you're driving, because you get less tactile feedback from a trailer than you do from the vehicle that's strapped firmly to your butt.

My opinion is that most drivers— when driving a vehcile they are fully accustomed to driving, at least— are more likely to be able to feel when something's not right with the drivetrain, and they'll have less need to rely upon gauges and idiot lights to tell them what's going on.
Well you seem to have higher opinion of the vehicle awareness of "most" drivers than the facts support. In fact over 30% of drivers have significantly underinflated tires on their passenger cars. I am aware of one study (thousands of data points) with the AVERAGE inflation of tires on that vehicle was 30% low, which makes it officially "flat".

I do not consider the TPMS to be in the relm of an "idiot" light, for as a tire engineer I know from experience that very few can sense a 10 psi loss, even when trying to evaluate vehicle feel. You are not an "idiot" or "unaware" if you pick up a nail or screw and your tire starts to leak air. A good sensor will advise you of the loss of as little as 5 psi in a few minutes. Other sensors may only warn after a loss or 20%. An early warning can give the driver time to react and stop before destroying the tire and possibly damaging the vehicle.
It is easy to be distracted from minor changes in vehicle ride forces. Even having the radio or AC on or having a pleasant conversation makes sensing the change very difficult.
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Old 04-04-2014, 10:17 AM   #36
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Mismatched tires on duals main issue isn't really the tall tire being loaded so much as it is with the tall tire covering more real estate per revolution. This causes the shorter tire to grab and skid causing the patterned cupping mentioned above.
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Old 04-04-2014, 10:29 AM   #37
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People disagree. Lol, what else is new.

Here is my take, if a person feels more comfortable with TPMS, then they should get TPMS, but I would strongly recommend sensors that are inside of the tire , not external sensors.

External sensors are in my opinion as big a hazard for getting a flat as road hazards.
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Old 04-04-2014, 10:32 AM   #38
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I still don't understand what you are saying in regards to safety.

I think I best leave this conversation because we seem to totally disagree on basic philosophy.
It appears to be my week for being misunderstood. I'm not saying that TPMS aren't good tools. I'm saying that I don't consider them essential. Just to be crystal clear, that means that I am not going to park my Interstate and refuse to drive it again until TPMS are installed. Which is what I consider the definition of "essential," as in "Don't leave home without them." So, from your irate response to my post, do I take it to mean that if you didn't have TPMS, you would turn your Airstream into a lawn ornament because you won't leave home without TPMS? Don't answer that! I'm just venting.

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Well you seem to have higher opinion of the vehicle awareness of "most" drivers than the facts support. In fact over 30% of drivers have significantly underinflated tires on their passenger cars. I am aware of one study (thousands of data points) with the AVERAGE inflation of tires on that vehicle was 30% low, which makes it officially "flat".
My opinion yields to your quoted studies. I stand corrected. Thank you.
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Old 04-04-2014, 10:33 AM   #39
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Thank you Tireman9 and Ag&Au. So the consensus is that these monitors should just be used as a guide only, although with time and experience we can get to understand their anomalies.
Peter
"guide only"

We can get into a discussion of semantics which will not be of much help to anyone.

It is true that each system has slightly different responses to operating changes. Some may be more sensative to sudden pressure changes than others. I know of one system that no only warns of a loss of air at the -15% from cold inflation set point but also gives a different warning if you loose 5psi from the Hot Pressure in a few minutes as I recall.

I have seen fairly quick pressure drops with the start of rain which drops the tire temperature and also the pressure.

It will not take the driver much time to learn the various responses of his system. An occasional tap of a button on the display will show the current pressure and possibly the current temp (+/- a few psi and a few degrees).

Don't get distracted with the display keep your eyes on the road and enjoy the trip. The TPM will provide faster and more accurate information and warning than any visual or manual inspection or IR gun or baseball bat rap on a tire after stopping.
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Old 04-04-2014, 10:34 AM   #40
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As for the original question that titles this thread,,,,, "are tire minders NEEDED?""

Of course they are not "NEEDED".
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Old 04-04-2014, 11:03 AM   #41
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As for the original question that titles this thread,,,,, "are tire minders NEEDED?""

Of course they are not "NEEDED".

Once again, a battle of semantics. Research "need", you will find a large number of defintions.

If you wish to use the definition that need means essential to life, then you will only need a TPMS on that day which you are scheduled to have a slow leak that leads to a blowout and you or someone else will be upside down and dead on the side of the road. Do you know which day that will be? I don't, so I use one all the time in case that is the day. Is that a need? Perhaps. According to how you interpret some of the many definitions of need, it may be.


To protagonist:
Sorry to disappoint you, but apparently you have not been around when I have been irate. That response was merely amused.


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Old 04-04-2014, 11:20 AM   #42
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Are TireMinders Needed?

Yea and we might be safer if we lived in a bubble too.

As a percentage very few accidents are caused by blown tires, and the fact is, most flat tires and blow outs result in no injury at all.

The fact remains, like it or not, TPMS is NOT "NEEDED".

It seems to me that a word as simple and basic as "need", in its common use doesn't require a lot of research.

I was thinking earlier that the title of the thread kind of invited controversy because of the word "need".

The op should have used a qualifier or two.
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