Tpms wtf?

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Andy

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I shouldn't expect anything less from a company that sells tire pressure sensors but I got a laugh out of this:

http://www.tpmsmaderight.com/direct_vs_indirect.php

"Research undertaken by fast.MAP on behalf of Schrader has revealed that 69% of drivers do not wish to undertake the responsibility of manually resetting an indirect TPMS system. "

Really? REALLY?

So customers don't want the responsibility of checking their own tire pressures then pressing a reset button within reach of the seated driver, to reset the system. Instead they prefer spending who knows how much extra for the sensors/antennas/control module in a new car, then what $300-500 for new sensors every 7 years or so, plus needing to have a scan tool and/or shop to initialize them. Not to mention the need to have duplicate sensors for any additional sets of wheels. I realize that part of my family's food on the table comes from VW/Audi's choice to use direct TPMS over the years (bless their hearts :) ) but I am ever so happy that my last three cars have had indirect ('03 MINI Cooper S, '12 Passat TDI, '15 GTI).

 
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Uwe

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I wonder though how well indirect will pick up tires that are simply neglected. Let's say all four are inflated to spec on a warm day in the summer. None have abnormal leaks, but come a cold the the next winter, they're all down quite a few PSI (and all about the same amount). A direct system will pick this up, but I'm not at all convinced that an indirect system will.

I think if I were writing the spec for an indirect system, I'd have it nag the driver roughly every 3-4 months, perhaps by turning the TPMS light one for a short while after the engine is started, and then turning it off. Keep increasing the length of time it stays on every time the engine is started if he ignores it. Hopefully this would get the fool to check his pressures and before he pushes the reset button to turn the light off. If not, well, then he's dug his own hole with respect to tire longevity.
 
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jyoung8607

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I shouldn't expect anything less from a company that sells tire pressure sensors but I got a laugh out of this:

http://www.tpmsmaderight.com/direct_vs_indirect.php

"Research undertaken by fast.MAP on behalf of Schrader has revealed that 69% of drivers do not wish to undertake the responsibility of manually resetting an indirect TPMS system. "

Really? REALLY?
Yeah, I think you found the problem already.

I imagine the question was something like: "Are you concerned about the OBAMA REGIME plan to take control and choice away from hard-working American drivers?"

Jason
 
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jyoung8607

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I wonder though how well indirect will pick up tires that are simply neglected. Let's say all four are inflated to spec on a warm day in the summer. None have abnormal leaks, but come a cold the the next winter, they're all down quite a few PSI (and all about the same amount). A direct system will pick this up, but I'm not at all convinced that an indirect system will.
You're correct - indirect systems won't pick that up. It can only look for differences between wheels. It'll work well to highlight a puncture or other slow leak that a driver might not be aware of, or perhaps give you a few seconds advance notice of an impending blowout. It won't do a thing for fuel economy due to seasonal inflation issues. Indirect systems are far from perfect, but the added cost and mass are darn near zero once you have four-wheel ABS/ESP, so there's virtually no reason not to have it.

I've seen proposals from at least one manufacturer to run with only two active sensors. Cuts the cost in half, and puts some firmer backing data behind the indirect TPMS algorithm, allowing absolute pressure to be determined for two and calculated for the other two. I think it didn't even care which two, so long as it had one on each side, which allowed for tire rotation.

Jason
 
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Andy

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Back when I was a reckless youth and drove to NJ to autocross my MINI, I pumped the tires way up all the way around for runs, then lowered them back down for the trip home. On the way back, the TPMS light would usually come on because it sensed a disturbance in the force. I think it's highly unlikely for all four tires (especially on a car without AWD and without perfect weight distribution) to change their effective circumferences at exactly the same rate and not trigger a light. Maybe along the same lines of probability as someone guessing a combination for a lock and defeating it, vs a key lock.

Car in question btw:

 
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Uwe

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You're correct - indirect systems won't pick that up. It can only look for differences between wheels.
If that were the case, I don't think they would pass the performance-based FMVSS spec, which I believe requires illumination of the warning lamp within 10 minutes if any (or all!) of the tires are 25% under pressure. Still, 25% is a lot of loss...
 
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Jef

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If all tires are low, the indirect system has no way to know. I suspect the easy fix would be to see what the GPS says your vehicle speed is, and if it doesn't agree with data from wheel speed sensors, then put up a check pressure nag message.
 
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Uwe

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If all tires are low, and it has LEARNED them that way, that's true.

But if they're all 25% low from the pressures the system was taught, it has to be able to detect this, otherwise it doesn't meet the FMVSS.

The tire pressure monitoring system must:
(a) Illuminate a low tire pressure warning telltale not more than 20 minutes after the inflation pressure in one or more of the vehicle's tires, up to a total of four tires, is equal to or less than either the pressure 25 percent below the vehicle manufacturer's recommended cold inflation pressure, or the pressure specified in the 3rd column of Table 1 of this standard for the corresponding type of tire, whichever is higher
https://www.law.cornell.edu/cfr/text/49/571.138
 
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Jack@European_Parts

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Well it is true...........
Most people don't want the responsibility of checking tire PSI and many don't even know what a gage is........ or how to check it.

I think Direct TPMS is superior option.

Unless some idiot does this............. Be on the look out for bombs like this in the car to detect fraud.

https://www.google.com/search?q=tpm...gtrucks.com%2Ftpms-sensor-canister%2F;793;424

http://www.hardworkingtrucks.com/tpms-sensor-canister/

DMV's have been known to bring a car in with one.
They do this to see if you actually checked the function and proximity of the sensor locations during a safety inspection.......... when pulling a wheel checking the brakes as a requirement.

You know to make money........

I have seen windows removed, seat belts, or even doors that are set to not open............ to setup the shop for a fine.

Entrapment!

But the deletes for emissions they seem to fail to enforce most of all...........go figure!
 
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Andy

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So a certain friend who will remain nameless who now drives a Prius (yuck!) says that one of the guys on his car's board put on snow wheels/tires without TPMS sensors. His solution to getting rid of the warning light was to place four working sensors INSIDE A PRESSURE VESSEL with the required air pressure in it and placed the vessel inside his car within antenna range presumably.

Edit: LOL, Jack beat me to it.
 
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vreihen

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I imagine the question was something like: "Are you concerned about the OBAMA REGIME plan to take control and choice away from hard-working American drivers?"
I'm surprised that the law wasn't written to also make the vehicle manufacturers provide tire pressure data to the NSA, where they would be stored in a huge searchable database to prevent terrorism.....
 
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Uwe

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Except I thought the primary reason people hated direct TPMS was because they were too cheap to buy replacement sensors when needed, and from that perspective, this doesn't really save them any money. If you're going to put them in a pressure vessel, why not put them in your wheels, where they'll do what they're designed to do?
 
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vreihen

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If you're going to put them in a pressure vessel, why not put them in your wheels, where they'll do what they're designed to do?
The second article that Jack linked to provided one scenario where a TPMS system is "just what they asked for, but not what they wanted." There are a lot of people (most on the left coast) who do driving off-road in the sand dunes and stuff. They intentionally lower their pressures for buoyancy on loose materials, and they apparently go low enough to trigger the TPMS alarms.

FWIW, I'm probably the only person crazy enough to willingly add an aftermarket TPMS system to my own vehicle. I bought it for the race car hauler tires, and wound up putting the sensors on my truck instead.....
 
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