Posted: 5/17/2015 6:23:49 PM EDT
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How does a car know what the tire pressure is?
Our new car displayed a warning that the left rear tire pressure was low this afternoon. Yep it has a screw in it. Should I take it to a dealer or will Sears or Goodyear be ok? |
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Well yes, but how does that sensor work and can any old tire store disconnect/reconnect it without screwing it up? Quoted:
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Each wheel has a sensor Well yes, but how does that sensor work and can any old tire store disconnect/reconnect it without screwing it up? a tire shop, any tire shop will take the tire off the rim, put a patch over the hole, reinflate the tire and the sensor will see that the tire then has air 
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Quoted:
Well yes, but how does that sensor work and can any old tire store disconnect/reconnect it without screwing it up? Quoted:
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Each wheel has a sensor Well yes, but how does that sensor work and can any old tire store disconnect/reconnect it without screwing it up? I'm pretty sure the tire guys are up to date, unless you find an old monkey who still uses his bare hands 
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Quoted: a tire shop, any tire shop will take the tire off the rim, put a patch over the hole, reinflate the tire and the sensor will see that the tire then has air Quoted: Quoted: Quoted: Each wheel has a sensor Well yes, but how does that sensor work and can any old tire store disconnect/reconnect it without screwing it up? a tire shop, any tire shop will take the tire off the rim, put a patch over the hole, reinflate the tire and the sensor will see that the tire then has air Nonsense. It's magic. You need a tire guy that can cast the right spell. |
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Nonsense. It's magic. You need a tire guy that can cast the right spell. Quoted:
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Each wheel has a sensor Well yes, but how does that sensor work and can any old tire store disconnect/reconnect it without screwing it up? a tire shop, any tire shop will take the tire off the rim, put a patch over the hole, reinflate the tire and the sensor will see that the tire then has air Nonsense. It's magic. You need a tire guy that can cast the right spell. And make sure he/she is Arcane spec. |
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Quoted:
Well yes, but how does that sensor work and can any old tire store disconnect/reconnect it without screwing it up? Quoted:
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Each wheel has a sensor Well yes, but how does that sensor work and can any old tire store disconnect/reconnect it without screwing it up? Tire pressure sensors have bee around since at least the early 90's. Any tire shop will have worked with them thousands of times over now. |
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TPMS
it is mandatory on new cars since I think 2007 or 08. after the low pressure tire, firestone/ford exploder roll over became big news. to prevent the unwashed masses that can't bother to use a pressure gauge from killing themselves due to under inflated tires, the .gov made it so you now must have this extra piece on your car. just like rear view camera's are mandatory. I don't rank this as the same as seat belts and air bags, not that those are much better, but at least they server a purpose to protect you from other drivers. this is like the warning labels, not to use a hair dryer in the shower or tub. |
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The sensor physically measures the pressure in the tire and sends the info wirelessly to the TPM module (on most cars) Some cars use a rotation vs tire height math equation and the ABS system. quit fucking with the guy, it's obvious that he doesn't know much about cars, much less tire gnomes |
| The TPMS sensor is in the valve stem and then there is a unit on the body that receives the signal. If the valve stem is removed from the rim you're supposed to use a rebuild kit when re-installing it, basically a new o-ring. Any shop can handle repairing the tire or mounting a new one. |
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The sensor physically measures the pressure in the tire and sends the info wirelessly to the TPM module (on most cars) Some cars use a rotation vs tire height math equation and the ABS system. NHTSA allowed that method for a few years while the MEMS (micro-eletro-mechanical sensor) technology matured, but new cars are forbidden to use the ABS sensors to detect tire pressure loss and must measure the pressure directly. I believe 2005 or so was the cutoff for cars that could use the ABS method. To the OP, there's an electronic module at the base of the valve stem inside each wheel that measures the pressure and radios it to the car. The batteries last about 5 years or so, and then the sensor must be replaced. The entire module is sealed to prevent moisture from corroding the electronics, so you can't just replace the batteries. Pretty much any tire shop can replace the modules when the time comes; they'll probably even have them on hand. When the first one goes, it's best to replace all four because the other 3 will probably also die in short order. |
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NHTSA allowed that method for a few years while the MEMS (micro-eletro-mechanical sensor) technology matured, but new cars are forbidden to use the ABS sensors to detect tire pressure loss and must measure the pressure directly. I believe 2005 or so was the cutoff for cars that could use the ABS method. Quoted:
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The sensor physically measures the pressure in the tire and sends the info wirelessly to the TPM module (on most cars) Some cars use a rotation vs tire height math equation and the ABS system. NHTSA allowed that method for a few years while the MEMS (micro-eletro-mechanical sensor) technology matured, but new cars are forbidden to use the ABS sensors to detect tire pressure loss and must measure the pressure directly. I believe 2005 or so was the cutoff for cars that could use the ABS method. Untrue.... My 2012 GTI uses the ABS system. Works very well except it doesn't tell you which tire is low. |
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Quoted: I think that's more of an option for your insurance. Quoted: Quoted: Your car knows everything. It even keeps a black box of your driving habits that can be used against you in a court law. No, really, "black box" info is often used in court cases. |
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Go to Walmart and get a tire plug kit. Pull screw, route out hole, shove in new plug, use a razor to cut off any excess plug hanging out. Fill tire with air. 9 bucks and you're prepared for the future.
http://www.walmart.com/ip/Slime-T-Handle-Tire-Tackle-Kit-9pc/16782763 |
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Go to Walmart and get a tire plug kit. Pull screw, route out hole, shove in new plug, use a razor to cut off any excess plug hanging out. Fill tire with air. 9 bucks and you're prepared for the future. http://www.walmart.com/ip/Slime-T-Handle-Tire-Tackle-Kit-9pc/16782763 Good idea, but this vehicle has less than 3K miles, I'm going to let someone fix it. |
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Good idea, but this vehicle has less than 3K miles, I'm going to let someone fix it. Quoted:
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Go to Walmart and get a tire plug kit. Pull screw, route out hole, shove in new plug, use a razor to cut off any excess plug hanging out. Fill tire with air. 9 bucks and you're prepared for the future. http://www.walmart.com/ip/Slime-T-Handle-Tire-Tackle-Kit-9pc/16782763 Good idea, but this vehicle has less than 3K miles, I'm going to let someone fix it. if it is that new, your dealer will probably take care of you for free. bumper to bumper for the first year or so no questions asked. give them a call and see. |
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Also, TPMS was government's answer to a problem that I never had. I look at my tires often, even still, with TPMS. All it did was add a couple hundred dollars to the car, and something else to go wrong. For example, 10 years ago, Chrysler vehicles used a bad valve stem that would break off at the first thread, make the valve stem useless, and requiring replacement of a $50 TPMS module/valve stem, plus programming charge. This lasted about 3-5 years, and I worked in a rental car business and these were the biggest pain in the ass to deal with. |
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Quoted:
Well yes, but how does that sensor work and can any old tire store disconnect/reconnect it without screwing it up? Quoted:
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Each wheel has a sensor Well yes, but how does that sensor work and can any old tire store disconnect/reconnect it without screwing it up? Yes, they can screw it up. They can also fuck up the sensor or damage it if they are careless. If they decide to rotate your tires for you, seems like most of the time the tire monkey has no idea how to reset the TPMS to tell the car that the tire has moved to somewhere else or does it incorrectly. Speaking of which, I found a nail in my tire (rental car), had to check all four tires for the nail since they fucked up the re-programming. |
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Quoted:
Well yes, but how does that sensor work and can any old tire store disconnect/reconnect it without screwing it up? Quoted:
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Each wheel has a sensor Well yes, but how does that sensor work and can any old tire store disconnect/reconnect it without screwing it up? It's a module mounted inside the wheel as part of the valve stem assembly, generally. Unless they somehow hang it on the tire changer and break it when dismounting/mounting the tire, it should be fine once the tire is patched or replaced and aired up properly. |