DaveTheAffable Posted August 21, 2012 Posted August 21, 2012 I'm in Denver on business. Picked up my rental car and saw the TPM was flashing. The young man/lot attendant deftly moved around the car with an airhose, and even though TPM was still flashing on the dash, he assured me there was "plenty of air in the tires". Down the highway I went.Tire Pressure Monitor on solid. The car felt "skittish" and had a rough ride to it. 7 miles from airport now... didn't want to go back. A quick stop to local tire shop... "Hey...can you check my tires?" A $5 thank you tip to the nice man after he LOWERED the pressure to 42psi from : FL 73 psi FR 62 psi RL 80 psi RR 66 psi TPM is off now. Car handles real nice. Rental agency "heard" from me. I was nice, and so were they.
DaveTheAffable Posted August 21, 2012 Author Posted August 21, 2012 Well, he was right...they had plenty of air Indeed... he was! And I learned that TPM can be triggered by over pressure. I'm telling on myself, but I didn't know that before today.
moshe_levy Posted August 21, 2012 Posted August 21, 2012 TPMs are now mandated in every new car. Some people aren't used to them yet. A coworker with a new Volt (she got one a week after seeing mine) freaked out at the TPM and left the car home when it went off, thinking there was something wrong. The left front was down 2psi. My brother's 2011 BMW 328i has a TPM that never shuts off. We've had it reset several times, and it will not turn off no matter how perfectly adjusted (or overfilled or underfilled) the tires are. New technology takes some getting used to sometimes. Bugs need to be ironed out and such. But your story is funny - hey, at least the gauge was working! -MKL
pbharvey Posted August 21, 2012 Posted August 21, 2012 Why are TPMs mandated on all new cars? Are people too stupid to check their tire pressure? Is it to force fuel savings? Do all new cars have mandated cruise control? Am I the only one here who uses two tire gauges because I don't trust either one of them? Do you think I'm going to trust a TPM?
Skywagon Posted August 21, 2012 Posted August 21, 2012 Due to my work travel, I rent a car two to three times per month. It is rare the tires have proper air...I see tires with 50 in some and 20 in the other in all kinds of variations. I now carry a tire guage in my suitcase. I don't leave the lot until the pressure is somehwhat in bounds. They usually tell me the tpm isn't correct. I hold up the guage and say, but this is...
Joe Frickin' Friday Posted August 21, 2012 Posted August 21, 2012 Are people too stupid to check their tire pressure? On average, yes.
Shaman97 Posted August 21, 2012 Posted August 21, 2012 Two tire gauges? Reminds me of the adage: "A man with one watch knows the time. The man with two watches is never sure"
Paul Mihalka Posted August 21, 2012 Posted August 21, 2012 Do the obligatory car TPMs just show a warning and don't show a the actual pressure number? That would be stupid. My $150 Tiregard on the bike flashes the pressure number when there is a problem.
OoPEZoO Posted August 21, 2012 Posted August 21, 2012 Do the obligatory car TPMs just show a warning and don't show a the actual pressure number? That would be stupid. Yes, and yes it is stupid. My '08 Jeep Wrangler just has an idiot light with an audible *ding*. On the other hand, Danielle's '08 Jeep Grand Cherokee gives you the actual real time PSI in each tire. So there you go......same year, same company, different result.
Mike Posted August 21, 2012 Posted August 21, 2012 I've had four vehicles with TPM. Two were on Subarus and one of the two constantly alerted when the tires were properly inflated, a real annoyance. The TPMs on my Jeep and BMW 5-series both work perfectly. They also can display actual pressures.
moshe_levy Posted August 21, 2012 Posted August 21, 2012 TPM experience with my personal cars is excellent. The two Priuses have a "dumb" TPM which just displays a warning, but a vague one that doesn't tell you which tire is low or what pressure is. However if you check, you WILL discover psi down at least 5 pounds from optimal. The Volt shows each tire's actual psi in real time, at a glance at any time (not just when one is low) - very nice! All have functioned perfectly. My brother's BMW 328i is another story. It too is "smart" TPM which shows measurement at each tire - the problem is the measurement it displays is totally off, and I've used 3 pressure gauges (some expensive and calibrated) to verify this. So the BMW TPS is what I call "smart, but dumb." FYI TPS is mandated for fuel economy reasons. Yes, the average person IS dumb enough not to check their tire pressure often enough, leading to dismal economy and premature tire wear. -MKL
Nice n Easy Rider Posted August 21, 2012 Posted August 21, 2012 Do the obligatory car TPMs just show a warning and don't show a the actual pressure number? That would be stupid. Yes, and yes it is stupid. My '08 Jeep Wrangler just has an idiot light with an audible *ding*. On the other hand, Danielle's '08 Jeep Grand Cherokee gives you the actual real time PSI in each tire. So there you go......same year, same company, different result. OTOH, if the idiot light for the TPM says you have a tire pressure problem, does it matter whether it is too high or too low? You're still going to want to check it with a gauge. My two cars have TPM and if one comes on I don't go anywhere without taking my gauge out of the glove box and checking. The idiot light is better than most on today's cars - at least you can narrow the problem down to one of four locations. My RT does give me an actual pressure but it is always 3 psi below the value I get using three different tire gauges but I know that and just adjust accordingly.
Skywagon Posted August 21, 2012 Posted August 21, 2012 My Tahoe gives each tire pressure + warning if low. My wife's new 2012 Lexus which touts having TPM only has idiot light.
1MPH Posted August 21, 2012 Posted August 21, 2012 Are people too stupid to check their tire pressure? On average, yes. I would say on average lazy. I like to think we're smarter than that.
moshe_levy Posted August 21, 2012 Posted August 21, 2012 I am impressed, that this far deep into this thread, nobody has hyperventilated that his freedom to drive around with no air in his tires has been violated by the endless meddling of mandatory TPS. -MKL
Joe Frickin' Friday Posted August 21, 2012 Posted August 21, 2012 Are people too stupid to check their tire pressure? On average, yes. I would say on average lazy. I like to think we're smarter than that. You'd like to think so, but... knowing that an important safety check ought to be done on a regular basis - and steadfastly refusing to do it - is stupid. OTOH, maybe I should point out my own bias and admit that I've made a value judgment, and acknowledge that other folks simply might not value survival as highly as I do.
OoPEZoO Posted August 21, 2012 Posted August 21, 2012 I am impressed, that this far deep into this thread, nobody has hyperventilated that his freedom to drive around with no air in his tires has been violated by the endless meddling of mandatory TPS. -MKL I actually removed the TPMS sensors from my Wrangler wheels not long after I bought it, but not for political reasons . The factory sensors have rigid aluminum valve stems that can easily be damaged by rocks when offroad. It can be fixed out on the trail by replacing it with a rubber stem, but it is a major PITA. Also......aluminum valve stem + steel wheels = big time corrosion issues around the valve stem. Stupid design
pbharvey Posted August 21, 2012 Posted August 21, 2012 The two Priuses have a "dumb" TPM ...The Volt shows each tire's actual psi in real time, at a glance at any time (not just when one is low) - very nice! All have functioned perfectly. . . . . . FYI TPS is mandated for fuel economy reasons. Yes, the average person IS dumb enough not to check their tire pressure often enough, leading to dismal economy and premature tire wear. -MKL I don't want this to turn political but its ironic to me that a hybrid car would require TPMs for fuel economy reasons. I understand the physics and the politics but in the real world to MANDATE TPMs on a hybrid seems illogical. Of course it also seems illogical to me that one of my BMW motorcycles has a recommended front tire pressure of 35.6 psi. No doubt something to do with the translation from bar to PSI but still, why drive people like me crazy trying to zero in on that .6 pound mark?
philbytx Posted August 21, 2012 Posted August 21, 2012 Our ever intrusive, Big Brother gubmint mandated it. Quote In the United States, the Firestone recall in the late 1990s (which was linked to more than 100 deaths from rollovers following tire tread-separation), pushed the Clinton administration to legislate the TREAD Act. The Act mandated the use of a suitable TPMS technology in all light motor vehicles (under 10,000 pounds), to help alert drivers of severe under-inflation events. This act affects all light motor vehicles sold after September 1, 2007. Phase-in started in October 2005 at 20%, and reached 100% for models produced after September 2007. In the United States, as of 2008 and the European Union, as of November 1, 2012, all new passenger car models (M1) must be equipped with a TPMS. For N1 vehicles, TPMS are not mandatory, but if a TPMS is fitted, it must comply with the regulation. unquote Once again, they decided that people are too stupid to manage their own lives and, unfortunately, in most cases they are
Quinn Posted August 21, 2012 Posted August 21, 2012 Just an observation: At any of the rallies I've attended with this forum, I've only seen maybe three people check their tire pressure before starting on the day's ride. One was me with a new patch in my tire, one was George with low reading on his TPS, and the other was an obvious low that was being pumped up. Surely I should have seen some of the self-rightous amongst us doing a routine check. -----
philbytx Posted August 21, 2012 Posted August 21, 2012 I check tire pressures on my bikes before every ride Then again, I am entirely anal
4wheeldog Posted August 21, 2012 Posted August 21, 2012 I would agree that regulating something like this would be unnecessary, if due diligence gave the same protections. But it doesn't........TPMS gives a warning while a tire is first losing pressure from a puncture, which is enough to give an early warning to an event not obvious to the driver. I actually think it is a good idea. Not having some soccer mom dealing with a blowout next to me on the freeway is well worth the expense. Just sayin'.
moshe_levy Posted August 21, 2012 Posted August 21, 2012 I don't want this to turn political but its ironic to me that a hybrid car would require TPMs for fuel economy reasons. I understand the physics and the politics but in the real world to MANDATE TPMs on a hybrid seems illogical. I do not see politics in your question, at all, so no worry there. But I don't get the reasoning behind it, either. The law is a blanket - it does not differentiate between this hybrid, and that non-hybrid, and so on. That aside, hybrid drivers are MORE anal about pressure than anyone, since low pressure reduces MPGs. Some of them check pressure religiously. Why would you think hybrids are immune from the requirements of TPS? -MKL
Joe Frickin' Friday Posted August 21, 2012 Posted August 21, 2012 Do the obligatory car TPMs just show a warning and don't show a the actual pressure number? That would be stupid. My $150 Tiregard on the bike flashes the pressure number when there is a problem. After some reading, I found that "indirect" TPM's infer tire pressure by measuring subtle changes in wheel speed and other properties via the ABS sensors. They can't tell you the actual pressure in the tire; instead, you reset the system when you know all four tires to be inflated correctly, and the system watches for changes in the signals it's measuring. The upshot is that indirect TPM's are very cheap to implement: add a few lines of code to the ECU's programming, and a light on the instrument panel, and you're done. Contrast this with direct TPM's, which require tire pressure sensors/transmitters, a receiver, wiring to power/interface with the receiver, etc. If your TPM is reporting actual tire pressures, it's a direct system, with pressure sensors inside the tires. If your TPM provides you with just a warning light, it's likely (but not necessarily) an indirect system.
pbharvey Posted August 21, 2012 Posted August 21, 2012 Why would you think hybrids are immune from the requirements of TPS? Not immune just that the incremental fuel savings due to TPMs seems small compared to the gigantic fuel savings due to a hybrid motor - hence no need for a mandate. If a vehicle is already getting >40 mpg why the need to mandate more? It reminds me of people ordering a diet Coke with their double cheeseburger and fries...yes it makes a difference but it becomes a smaller piece of the whole.
Paul Mihalka Posted August 21, 2012 Posted August 21, 2012 Even on a hybrid I would like a warning on the road that one of the tires is down to 20 lbs because of a nail, while without TPM I'd be driving until the tire is flaaaat....
moshe_levy Posted August 21, 2012 Posted August 21, 2012 Not immune just that the incremental fuel savings due to TPMs seems small compared to the gigantic fuel savings due to a hybrid motor - hence no need for a mandate. If a vehicle is already getting >40 mpg why the need to mandate more? It reminds me of people ordering a diet Coke with their double cheeseburger and fries...yes it makes a difference but it becomes a smaller piece of the whole. Agree that hybrids by definition usually have better fuel economy, but the same principle of losing MPGs to underinflated tires applies, so as the saying goes, "why not?" Hell, you and I know that were a fleet of underinflated hybrids running around, the next thing we'd hear about is how lousy their mileage is! And don't forget, TPS was mandated more as a response to safety / blowouts as Mitch said, not MPGs primarily. Once again, hybrids are just like any other car from that point of view as well. -MKL
DaveTheAffable Posted August 21, 2012 Author Posted August 21, 2012 Hi... OP here... Does any one have any comments about safety related to at least one tire being at 80 psi?
moshe_levy Posted August 22, 2012 Posted August 22, 2012 Oh... Oh yeah! That COULDN'T be a safe pressure. Glad nothing exploded on you, Dave. Sheesh... Can't believe they had them at that psi... -MKL
tallman Posted August 22, 2012 Posted August 22, 2012 Hi... OP here... Does any one have any comments about safety related to at least one tire being at 80 psi? As long as you underinflate the opposite tire it should handle fine.
4wheeldog Posted August 22, 2012 Posted August 22, 2012 I bought my first TPMS vehicle in March of this year. It is a Subaru, with no pressure readout. However, from my reading, it does have sensors in the tires, as well as monitoring the rolling diameter of the tires, as they relate to each other. One of my buddies also has a new Subaru, and he managed to trip the light by driving in tight circles......(Don't ask......I didn't.) The system makes sense to me, and since I have a quality gauge in/on all my vehicles, it is not a huge issue to find the problem donut if and when the light comes on.
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