Tire pressure alarms

The local TV news announced that all new cars sold in US after this summer would include built-in devices to warn about low
tire pressure: more automotive electronics. I found a paper by NHTSA that describes the two techniques for accomplishing this. Interesting reading. I decided to either buy a new car right now, or wait a few years until this stuff is either improved or eliminated.
Have a look for yourself: http://www-nrd.nhtsa.dot.gov/vrtc/ca/tpms.htm
and this report linked there: "Examination of Existing Tire Pressure Monitoring Systems"
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The government is clearly out of control. The reports points out that if the tires are not perfectly matched these systems will falsely trigger based on rotational speed mismatches. The same is true if you are running chains or just spin the tires a lot on slippery surfaces
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Clearly, government again responding to a "there oughtta be a law" request. After all, what good politician would vote against such an obvious safety feature? qc:
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Al, the usual


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snipped-for-privacy@aol.com wrote:

That's the solution that compares effective radius of tire pairs by differencing the wheel pulsetachs (already there for antilock brakes). It's appealing because there's no added hardware (except display). But it alarms only in response to wheel pair speed differences: it would be perfectly happy with all four tire running at 5 psi (or totally flat)!
I got the impression that the industry was leaning toward the other scheme: radio telemetry from pressure sensors, either inside each tire or screwed onto the existing valve stem. Battery powered, with individual codes for each sensor so that the main computer knows which tire is low. This also avoids interference from nearby vehicles having similar blessings. Sensor replacement (e.g., dead battery) requires a visit to dealer who has the special box that tells the main computer about the new code. The dealer also has the stuff needed to unmount, remount and balance the tire if you have the sensor-inside solution. Bring money.
Oh yes, one reports cautions that these tire pressure monitors are not intended to warn about blowouts. I'm glad they told us.
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the lawyers told them to add that to the product announcement (c:
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Al, the usual


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Usual Suspect wrote:

Do you think that'll cover their butts in a civil case? There are directions in every owners manual that I've ever seen cautioning owners to check tire pressures or risk hazardous conditions. Nevertheless, someone gets hurt due to a blowout and there's a lawsuit.
Now, cars are equipped with a 'warning system' that doesn't warn about all possible hazardous conditions. Owners think they don't need to worry any longer and forget about checking the tires. Now the auto company gets sued for lulling divers into a false sense of security.
One condition that worries me is that the wheel speed sensor technology won't catch a condition involving all tires going flat at the same rate. Owners STILL have to check pressures manually.
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Paul Hovnanian mailto: snipped-for-privacy@Hovnanian.com
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The tire industry prefers direct pressure sensors becuase they generate better information. The auto industry favors ABS-based indirect systems because they are cheaper.
The big problem for the consumer is that there are no standards yet. Even within one make there can be different types of sensor systems.
Sensor replacement shouldn't occur very often - battery life on these systems approaches 10 years. The bigger issue is when you get your tires replaced and the mechanic breaks one of your sensors because he hasn't seen that specific type before. It's a mess, but since the systems are mandated by law we're stuck. And by they way, it's illegal to knowingly break of diasble the pressure monitoring system too...
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snipped-for-privacy@gmail.com wrote:

How would the authorities know? In this state at least, many counties have no vehicle inspection (it's mandated by EPA air quality). I can't imagine the system disabling the car until the sensor is fixed, and without some form of enforcement, a lot of broken systems will remain so.
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On Mon, 19 Mar 2007 16:05:53 -0500, snipped-for-privacy@aol.com wrote:

My 2000 Monte Carlo has this feature as standard, so we're not talking bug-eyed technology here.
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wrote:

So does my '05 Tundra.
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wrote:

FWIW A friend with a 'vette says he had to look around for the right version. Apparently they were available for some time, but different radio/pressure sensors are not always compatible with his car.
And the batteries don't last forever. His were completely 'potted' in the casing and could not have the batteries replaced. He shipped them out to some after-market outfit that cut them open, replaced the batteries and sealed them without potting compound for a small fraction of buying replacements.
daestrom
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