fun with tire pressures

I use rechargeable 9V batteries instead of regular alkaline ones for most applications. All of mine use nickel metal hydride cells. That poses a bit of a problem, as the voltage per cell is somewhat less. However they are actually sold in versions with either six, seven, or eight cells. I don't recommend the versions with six cells as they always put out appreciably less voltage than will the alkaline version unless it is at death's door. The seven cell versions work nicely in most applications and are easy to get. I use the eight cell versions in a couple of applications that both need some extra voltage, and will tolerate considerably higher voltage when freshly charged.

It does not take very many uses to save back the extra cost of the battery and charger.

AA and AAA, I have Panasonic rechargeables, NiMH, again from Costco. But not 9V. I prefer devices which have Li-ion built in...say if this tire reset tool were rechargeable, that would be king. If it cost $90 it should be, but $10, no.

Remember the days of Ni-Cd power tools and flashlights etc.? I've purchased ones that were bum right out of the box, and they never totally worked well. Amazing how far we've come in 20 years.

Unfortunately there are items that come only with batteries built in. The drawback in my opinion is, since no batteries last forever and rechargeables have a certain lifespan it is almost impossible to get a new battery installed once it fails.
Now you have to buy a new item !!!

My '17 Ford uses sensors in the stems.

If I follow you there is some measure of wheel rotation that is a proxy for pressure. What could that be? The only thing I know of that measures wheel rotation is part of the ABS.

I have a 2006 Toyota which btw it had a flat and no warning, but it does not use sensors and it does not tell psi either. Which is great since when I put the snows on I don't need to buy sensors. My 2007 BMW uses sensors, and it knows where each one is, I was low once and the dash had an icon showing where on the vehicle it was, no psi. Many of the rental cars I've gotten last year, takes minutes before PSI shows up, until then, dashes. I am pretty sure the abs sensors are used in determining psi. My wife's had all dashes yesterday which was bothersome...as I could have lived with the mismatch.

Again likely many of us drive sticks, learned to drive without abs and airbags, etc. So on my BMW I have no sensors in snow tires and don't care, the warning is on all winter...

seems to be no choice! My 2015 ThinkPad has 2 batteries, one removeable. My 2020 ThinkPad only built in. But I watched a YouTube and it's not hard to replace. Still one hates to open up unnecessarily, especially on a phone.

Anyone ever change a watch battery themselves? Not good hahahahahahahahaha as in ruined the waterproof seal. Though my watch for the last 13 years is automatic, not quartz

I've ridden in a relatively new Honda that uses rotation sensing to satisfy the federal requirement for low tire pressure warning.

Reading between the lines a little bit, I think the basic trick is that you are supposed to tell the system when you make a tire or pressure change. Subsequently it uses the next bit of driving (maybe 20 miles or something) to learn what the current relative rotation of all four tires is. Subsequently it monitors things to see if one of the tires moves out of the learned relationship to the other three.

The big hole in principal is that if all four tires lose pressure in sync it will not notice. In practice that is not how real world tire pressure problems normally behave.

Not needing to replace the sensors and not needing to make sure the sensors and the car are in proper communication are both huge pluses. I'll be happy if my next car has this type of alerting.

Tire pressure monitoring systems (TPMS) are of two types; direct and indirect. In the direct system there is a device actually in the tire that measures the actual pressure and provides a display of that value. In an indirect system a physical sensor is not used, but the indirect system measures air pressures using software-based systems, which by evaluating and combining existing sensor signals like wheel speeds, accelerometers, driveline data, etc. estimate and monitor the tire pressure without physical pressure sensors. In the United States, as of 2008 all new passenger car models released must be equipped with a TPMS

Obviously the direct system is related to wheel position, and in the indirect it generally isn't. The direct is more expensive and often needs to be replaced when tires are replaced.

Calibration method may vary. In the Honda indirect system from about 2013 you place the vehicle into a calibrate mode, and change the tire pressure by about 5 psi. Not easy to do at home, unless you have some form of compressor.

Back in 2008 when I bought snow tires and rims, I opted not to get sensors as I forget but they were like $250 more. No big deal.

today, if you go to buy tires/rims, and you don't get the sensors, you check off a box that goes something like "I intend on purchasing the sensors separately and will have my installer put them in." This isn't logical as you're getting the tires mounted/balanced on rims from the online etailer already. I guess it's for them to protect themselves.

Another thing I noticed as I rented many cars in 2019 for business and got loaners as well. For some reason they are blowing the tires up to like 51 psi? wth? First thing I do when I get a rental is to check, and release the pressure to factory recommended....

I'm one of those folks who feel that cars peaked sometime around 2004-2010. After that, they went downhill. Lots more tech, but the build itself is cheap. You can even go up to the 70k range and find cars with solid rear discs. Look at the brakes on a 100k American car that isn't a performance car--puny and cheap.

If cost is no object then sensors are better, but in reality, just think....say every 4 years you get tires. Do you, or do you not, replace sensors, if sensors are $50+ each and they might last 8+ years? What if it costs $30/rim to mount and balance? As long as you are ok with throwing away $300 (most of us are not), then it's a hassle....we don't really want to throw away good sensors. I have no idea how long the batteries last, I changed them when my car was 8 and they were still good, but I figured at some point they'd fail, so I did them when the tires got changed....at least I bought them online....

The reality is know your vehicle or you could get ripped off. I'm not agreeing with what Tire Rack states but quoting from their website

So a Lexus, Infiniti or Toyota could cost $40-$160 per sensor and require a trip to a dealer for "initialization." Bet that isn't free! Often times the stuff about initialization is garbage but not owning one I can't say for sure.

my Prius sensors lasted about 170,000 or 4 sets of tires. They were $90.00 installed for 2. Then they replaced another one for free. Bottom line, IMHO, sensors should cost about $30 installed. You can buy them for about $10. but they make a big thing about mfg original or approved, but they are all the same. It is also very trivial to register them.

This is insanity. I clearly remember saying ah man I gotta pay $200 for set of TPMS, but I'd rather do it while the new tires are going on. That place I got them from, is out of business, lasted 1974-2019, existed when I was a kid. Now the sensors are $100 each list and $72 discount? Pretty sure I won't be getting them ever again! Car is a 2007. Rockauto has aftermarket from $50+, but back in 2016 I got OE for $200 complete set....bet you supply and demand. Little demand.

Looked up my wife's, $28 aftermarket, $42 OE. I'd go aftermarket and would be worth $120 or so for 4. I wonder if Costco really replaces the valve? They include a kit on the work order, and the charge is waived since my wife's tires were a warranty replacement (got 43k on 60k warranty = $262 credit).

Thanks for bringing this up. I've enjoyed learning about it.

from: https://www.edmunds.com/car-safety/tire-pressure-monitors-ca...

"There are two types of TPMS: indirect and direct. The lower-cost, indirect TPMS doesn't actually monitor air pressure. Rather, the indirect TPMS uses the antilock braking system's wheel-speed sensor to detect that one tire is rotating faster than its mates. (An underinflated tire has a smaller circumference so it has to roll faster to keep up.) Thus, there's a large margin of error in indirect systems."

likewise from: https://auto.howstuffworks.com/car-driving-safety/safety-reg...

"Indirect tire pressure monitoring systems don't rely on sensors to do the work, or at least not pressure sensors. The systems rely on wheel speed sensor data to interpret the size of a tire based on how fast it rotates -- a small tire would rotate faster than a larger tire, and an underinflated tire is smaller than one with proper inflation. All of this data can be gleaned by electronic monitors within in the car, and then interpreted using advanced programming and processing."

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I checked Tire Rack and sensors for my ‘17 F-350 cost $32/wheel. Discount tire had three from $82 each to $100.

Most of the few days per week that I drive I check my tire pressure using the sensors. I find it reassuring that the tires on the sunny side have a somewhat higher pressure when I start out.

Think alike....I've noticed that too. Also to me, nitrogen still changes by 1 psi per 10F, no different than air. So in my wife's case the front was on the back and the back on the front. My hunch is that costco keeps the tires on the same side of the vehicle, although the diagram on the paperwork shows another pattern....in my lifetime, it only mattered once. That's where I noticed my other car had an icon of 4 tires and a red triangle showing the one that was low. It doesn't have any psi reading. My toyota plain doesn't work at all, my tire was down to 16 psi and nothing haha

Our 2014 Chev Orlando & 2019 Chev Trax use sensors. I always go to the dealer, but they even forget to set the sensors sometimes.

The TPMS on my wife's 2012 Suzuki Grand Vitara drives me crazy. The system is too sensitive. Just one tenth of a PSI sets off the warning light! I had to buy a super accurate tire pressure gauge and fill each tire to the exact same pressure to get the light to go out.

Once set, it doesn't last long. whenever there is a significant temperature change, I have to reset it again. I'm about to use the "black Tape" fix and cover up the light.

At this point, it isn't worth getting it repaired since we are new car shopping and plan to replace the vehicle.

It sounds like a reset/relearn procedure is necessary. This isn't the same as a reset process to clear a dashboard warning light and it involves a relearn tool. Suzuki's method of you getting back to the dealer where they can charge you $100 and talk you into other work.

This by the way is why places like Costco often don't do a relearn procedure. They simply don't have the relearn tools for all cars.

Here's the procedure from the manual:

One thing I have learned in doing these procedures is do them exactly as stated or they sometimes fail. For instance it states to "set the parking brake". Many people may not do this as the car is on level ground and is in PARK on the transmission. However, the parking brake has an interlock switch that may need to be actuated.

Also, on an 8-year old vehicle, if the sensors are original, I'd be replacing the sensor batteries or sensors. But again the dealer would love you as a client, as the sensors for that model year are about $30 each (or more depending on source) or $110 for a set of four. See https://tpms247.com/collections/2012-suzuki-grand-vitara

Long story short I was frustrated the other night, I mean I could have pretended there are no sensors (in which case doesn't matter the front is really the rear, rear really the front, left and right is correct), because the "i" button has to be pressed to see the psi's. But after my first go round, now the car has warnings right off the bat, and a tire icon lit.

I think that many advances over the last 20 years are good, many are not. Sensors in the tires, lack of a dipstick in automatic transmissions, no more manual transmissions, cars that park themselves, cellular connected cars, run flat tires, these are all bad things. They encourage bad behavior if you will.

Conventional wisdom says to check tire pressure every few days, with a gauge especially if the weather changes. Check oil level. How many might "eyeball" the sidewall and say I think I need air, and go to the local convenience store and rely upon an inaccurate machine?

I used to have a coworker and his kids were 5 and 3 in 2014. He said my kids will get their licenses when they can a) change a tire b) change the oil c) drive a car with a clutch

Then he says his wife told him the son's getting a Mustang GT when he's 16.

I would say dad and mom have two different perspectives, and that many today think like the latter. I would think the majority of the car driving population cannot change a tire or oil, and might not even know what a clutch even is...

my 2011 Ford Escape and 2015 Ford Focus (Both Titanium) each have low tire inflation sensors, but when they come on, All I know is ONE TIRE is low, but I'm not sure Which One!!!

I did rent a car one time that told me Right Front tire was low...
and I put air in it twice before realizing that the one that was low had been rotated from Right Front... but wasn't low enough to be seen by eye, an I obviously didn't have a pressure gauge with me....
Took back to Rental car place.... They reimbursed me for Air cost, and checked pressures, removing much air from right front due to my 2 additions (no gauge at places I added air)...

The intended purpose of TPMS legislation has long been lost. With respect to your Ford products, examine the procedure at https://www.ateq-tpms.com/en-us/article/tpms-information-for.... As you can see relearning the sensors is a elaborate process. So the alternative is do without, and buy a roll of black tape.

On my 2013 VW Tiguan if you change the tire pressure then you just tell the car to learn new pressure, If you get a low tire warning then you just check the tires for a leak and add more air

this is how my Lexus is supposed to work, which when I got it used in 2016, I was happy since I was getting snow tires and rims and no need to spend more on sensors. But I've since discovered the system doesn't work (had a flat and no warning). Others on the forum report the same. Maybe it's old technology because the car is a 2006 but it came out in 2001 so we're almost talking about 2 decades old technology. But it's one of those cars that last forever--some online went over 1 mil miles. Easy to work on at home which is a plus too. Sometimes old = good!

Lexus back n 2006 said the batteries in the sensors lasted “about 10 years” so you are overdue, unless of course you had the sensors replaced. There are some junk 3rd party sensor out there, I always recommend Schrader or OEM. It is very rare that I get any issues, other than those I can trace back to pilot error.

I’ve been licensed to drive since the early ‘60s and in ‘11 bought my first vehicle with a slush box. (Slush box, in case you don’t know, is a pejorative for automatic transmission.) For towing I didn’t see a real choice. Now that I’m used to it I find no faults. My last concern was using the cruise control while driving in snow. My specific worry was that on an uphill e.g. an overpass, it might downshift and apply too much torque and I’d lose control. Solved: put it in manual mode. The only remaining virtue and one that one of my kids is sold on is that a thief has to know how to drive it! OTOH with the auto’ my wife who almost never drives can drive.

I’ve had one TPMS episode. Returning to the truck a rear tire that is ordinarily 80 psi cold was at 30 and the klaxon alerted me. Visually I could see no deformation but found the nail. Finding it then rather than some time after arriving home was very convenient.

My tire store, Discount Tire, tells me that on my ‘17 F-350 that the TPMS will re-learn the sensor locations by driving. I don’t believe them and ask them to go thru the re-learn process by hand and they humor me. I don’t want to go back to the store after discovering that they were wrong. I’m really interested in hearing any thoughts about my being wrong.

I bought an aftermarket reset tool which is supposed to be compatible with the Suzuki but it didn't help. The instructions are different that those you outlined though so I'll give it another try.

It isn't worth wasting a lot of time though since we're new car shopping.

That the GM basically once in reset mode, wanted a signal at LF, RF, RR, LR, and would light up a parking lamp at each position. And really I wasted lots of time waiting with the thing transmitting, as I was pointing the antenna at the valve stem, as if adding air. I thought after a long time I got a honk.

But as soon as I placed the antenna at the rubber sidewall, about 1" in towards the center of the wheel, and in the area of the valve stem, it was an instant honk. That's what worked for me...good luck!

I am becoming happier every day, none of my vehicles have any sensors other than ABS. 01 f150, 99 Nissan pathfinder and a 1985 e350 Motor home. want nothing to do with this new shit, would rather have manual everything but can't find that anymore. GF got a 2006 chevy colorado and it still has manual windows and door locks, can tell the grand kids to crank down the window ha

Even though I have the reset tool, I don't use it much anymore. When the TPMS light indicates low pressure in one tire, I check them all. I have to get out the gauge and air hose anyway so it's no big deal.

This has been discussed here before but just in case you missed it, automotive TPMS systems are being used to track vehicle movement:
https://www.schneier.com/blog/archives/2008/04/tracking_vehi...

Among other things, TPMS is used to control those highway signs that give time & distance to a location ahead.

Just another tool for Big Brother. It makes me wonder if this is the real reason the government required TPMS on all vehicles sold after 2010.

If you have a low tire light then you should check all tires anyway

If this is the case, then the one's which don't have a sensor, would be better. Unless the ABS sensors connect to the internet, one just never knows.

Again, my 2020 ThinkPad connects to the internet (one drive blah blah etc.) and I know every action can be documented. Part of me doesn't care, the other part says I'm glad my 2015 ThinkPad isn't as such.

Well my car is a 2015 and does NOT have TPMS.(NO electronic sensor in the wheel). The way they do it is by somehow knowing that a tire with low air causes more drag and the computer can tell that.

This is still a form of TPMS. Although not electronic and therefore not trackable, it meets the government requirement.

My wife's car is a 2011. It tells you if you have a low tire but doesn't tell you WHICH tire. D'Oh!

Here is the insanity
https://www.aliexpress.com/item/4000123306887.html?spm=a2g0o...
$36.00 for 4 pieces for Toyota. Others are similarly priced. Changing them out while new tires are being installed must take all of 1 min each. Registering them is less than a 5 min job. Of course, you must have the tool, which anyone who does their own work on their auto should have. So, what SHOULD a shop charge? 30% markup on the parts and 15 min labor == that is about $50. being generous.
Set of 4 == $86.00 installed.

I'd like to understand that better. I have great respect for Bruce Schneier but I must confess that I haven't been following him recently and I don't remember this blog entry from '08.

In https://en.wikipedia.org/wiki/Direct_TPMS I fount this: "... Another method of attempting to avoid collisions is simply to transmit more frequently such as once per minute. ..."

Continuing with the idea that the upper limit of an individual TPMS sensor is once per minute then for all four wheels is once per 15 seconds. When driving at a mile a minute a signal with one of four different identities is transmitted on the average of every ¼ mile.

The same wiki entry says that the typical transmit power power from a sensor is 250μW. That sounds very hard to detect at a distance.

It sounds unlikely to me that a surveillance system using TPMS would be implemented. Since license plate readers are already commonplace who would spend the money?

Does anyone here know if such a surveillance has been implemented?

My 2013 Jeep Wrangler Sahara JKU has a display that tells you the pressure in each tire ... 35, 35, 35, 35. The full size spare mounted on the back does not show.

I recently changed the wheels (not tires) and had a new "TPMS Valve Stem" put on each of the 5 wheels at a cost of $7.61 each.

I've never had one get low enough to trigger the alarm but I do see fluctuations in the psi due to use (driving) as well as the temperature outside.

My example above is what the manufacturer says the cold psi should be. I've never gotten them all to show the same number cold, one might be 34, another 36, etc. I guess they are really really sensitive because my gauge says they are all the same when I check them.

.

It may surprise some, but parking a car in the driveway can cause pressure differences of about 2 to 3 psi just due to the tires on one side being in the sun and the other side in the shade. Certain things can make for even wider variances; for example July sun at 2 PM on one side of the car and the other side shaded by a tree since early morning.

surprise 1 psi for every 10F. I dunno two things I definitely remember from HS is v = ir and pv = nrt. As a 16 y.o. we don't know how it matters in the real world, as an adult, we do.....

I just replaced 8 dome lights in my wife's SUV because one burned out in the cargo area....10 LED for $7.19, when the 2225 is $7 locally for 2, or $4.49 at amazon. Not only 3X brighter, white, but 1 watt instead of 5, per. v = ir! i thanks me.

With my wife's GM--check with a gauge that does 1/10 of 1 psi, all 4 tires exact. Starting off, they seem to be off, sometimes as if it is reading what it did when last driven--i.e. higher. Drive for a while and then going forward, all 4 are same. One thing about tpms, they are not reliable. Because you want to know when you start off, not 5 minutes into the drive, that you have a problem...

I have experienced that and was including it in the temperature making a difference I mentioned. I check mine with a gauge before sunrise, I'm an early riser, head for work before sunup most days. For times when it is in the sun once you drive for 5 or so minutes all the tires end up fairly even.

My Jeep is the same, yes it still has the reading of when you parked. For my jeep it takes about a quarter to half mile for them to reset.

This is from my Jeeps manual:

The Tire Pressure Monitor System (TPMS) consists of the
following components:

• Receiver Module
• Four Tire Pressure Monitoring Sensors
• Tire Pressure Monitoring Telltale Light

A tire pressure monitoring sensor is located in the spare
wheel if the vehicle is equipped with a matching full size
spare wheel and tire assembly. The matching full size
spare tire can be used in place of any of the four road
tires. A low spare tire will not cause the “Tire Pressure
Monitoring Telltale Light” to illuminate or the chime to
sound.

The “Tire Pressure Monitoring Telltale Light” will
illuminate in the instrument cluster, , a “LOW
TIRE PRESSURE” message will display in the
EVIC, and an audible chime will be activated when one
or more of the four active road tire pressures are low.
Should this occur, you should stop as soon as possible,
check the inflation pressure of each tire on your vehicle,
and inflate each tire to the vehicle’s recommended cold
placard pressure value. The system will automatically
update and the “Tire Pressure Monitoring Telltale Light”
will extinguish once the updated tire pressures have been
received. The vehicle may need to be driven for up to
20 minutes above 15 mph (24 km/h) to receive this
information.

I have a (relatively) expensive tool that connects to the ODB port as I have 4 cars with sensors and put snow tires with sensors on in the winter. I rotate and swap the rims myself. Had a little snow today so it is time to do it soon.

Funny thing is that the cheapest of the cars, a 2009 Kia Sportage remembers two sets of sensors and after driving a few miles automatically syncs the sensors back up with the car.

Wife got the "Service Stabilitrak" warning, I decided to pay $85 for a reader that did ABS/airbags. I actually didn't believe it would work. Because I had paid $160 a few years ago for one that did ABS/airbags, and it could not communicate with my 1998 Nissan, even though the manual specifically said it could. Returned that one. My guess is the car was too old.

This one worked! Replaced a $7 part that looks like a fork and attaches to the brake pedal. If you ever see a GM (man these cars are riddled with issues) going down the road with its brake lights on, yet it's not braking....

Then when the battery died a month ago (this didn't happen when battery replaced 2X prior), an airbag warning was present that did not go away, yet the reader could read and reset. The sensor that disables the pass side airbag when nobody is sitting there, lost communication with the module per the error. Ever place a cell phone on the pass seat, and have the airbag enabled?

The BMW I have the dealer software so of course that does a lot of advanced stuff, but it DOES NOT CODE. Needed it to do the ABS pump job. It's windows based and a train wreck. Most guys use the DOS based program which is easier to use.

Interestingly, many people are OK with buying things that cost many dollars over many years, but they don't want to invest in a battery tester or OBDII devices. Once I told someone get a $14.95 one, at least you can read I/M readiness and reset, and the response was nah, I don't want to spend that on something I may use once lol It's as basic as a thermometer to read one's forehead I would say.

p.s. uncle had one that was in the $5k ballpark made by Snap On. He wanted us to take it from Chicago to NYC back in '15. I said I haven't got any room for carry-on. Last time I put a tablet in my checked baggage, it was gone. He said just put it in your baggage, the TSA isn't interested in my Apollo. I guess they likely had no use for it or didn't know what it was because it was here when we got to Phila. We drove it to NYC a couple weeks later.

p.p.s. my wife's car went into I/M readiness = yes yesterday....took about 370 miles. So we can finally get our car inspected on Thu.