Although looked down upon, and looking very technologically backward, the tires are actually one of the most critical elements in a car (old cars did have tires, but did not have airbags, for instance). They are one of the most important factors in driving on various surfaces (dry or icy) and are vital system components when trying to prevent accidents. Incorrectly inflated tires are known to have contributed to a significant percentage of road accidents. Even when not producing any straightforward accident, low pressure tires continuously harm the environment by increasing the carbon dioxide emissions of the car (and correcting it is completely costless and easy, as long as you know the car has a problem). To assist the driver in this respect, tire pressure monitoring systems (TPMS) are employed in many premium cars today.
So significant are the effects tire pressure has on the overall behavior of the car that word goes about of making TPMS (Tire Pressure Monitoring System Solution) mandatory for new cars sold in Europe as early as 2012. The final decision in this respect will be taken during the first half of this year (2009) being driven also by environmental friendly groups which argue that incorrect inflated tires generate CO2 through the additional fuel consumption determined by an increased rolling distance and resistance of the tire.
There are currently only a handful of suppliers in the automotive market offering major carmakers customized TPMS (out of which at least one, Continental, is directly affected by the recession which influences the entire industry). Together they have sold a significant number of such systems in 2008 (in tens of millions) and they all realize that they compete for a market in which demand could explode, should pressure monitoring be required by legislation.
Already such systems are mandatory in the US starting with the first month of 2008. According to the law, a pressure drop of 25% is considered acceptable, but not anything less. The people working on European legislation are aware that this value is too high for Europe, where higher speed limits are in place (especially on German motorways). The final figure that will be in place for Europe will probably be below 15% to account for these high speed limits. Under such circumstances, monitoring the pressure in an easy manner is critical, as tires are known to lose pressure just by the diffusion of gas molecules in the rubber, or through leaks caused by faulty valves.
There are extensive studies conducted both by various European Safety Authorities or by TPMS supplier companies (obviously in a bid to convince the carmakers that what they sell is needed) showing various figures of accidents caused by incorrect tire pressure (in France, for instance, these studies claim that almost 10% of road accidents could have been averted by having the tires correctly inflated).
Not only safety is a major concern driving this technology into cars, but also the effect on the surrounding environment is an important consideration. Research has shown that tires with a pressure deficit of over (but close to) 15% would lead to increased resistance to rolling and thus to an increased fuel consumption of about 5%. This becomes an important criterion in a market where major players advertise their cars as having small carbon footprint and where car taxes paid by the end user of the car might be determined by the CO2 emissions of the vehicle they own.
Although TPMS sounds very technologically advanced (and it is, because it evolved), the idea and implementation have been around since the mid 1980s (introduced by Porsche); they only started to be offered as standard equipment during the very end of last century. Today most carmakers offer this feature on their car either as an option or as a standard, on more expensive cars. Many of them do it, though, just to keep up with the competition, as not all of them are convinced of the reliability and accuracy of the measurements.
This is especially true regarding indirect TPMS. These are systems consisting mostly of software applications and using elements in already existing car systems (like for instance ABS speed sensors, which are installed as standard or ESP system elements). The cost advantage of such systems is obvious, as once developed, software does not cost anything. What earns the nomination of “indirect” for this method is the fact that the tire air pressure is actually computed from other variables measured outside the tire. Older versions of indirect systems would only be able to tell when one of the tires would be under-inflated taking into account the increased rotational speed of that tire, which would be determined by the slightly smaller diameter of the tire itself. To overcome this disadvantage newer versions have been developed, capable of detecting decreased pressure in more than one tire, by making a vibration analysis of all four wheels, or by analyzing the load shift during acceleration/deceleration. Indirect TPMS also has the disadvantage of requiring a “system reset” at a good moment in time. The driver is actually required to mark (either through the push of a button or through dashboard controls) the moment in time when all wheels are correctly inflated. If the driver does that when one of the tires has a slightly decreased pressure, this will negatively influence the correct functioning of the system. Indirect TPMS is the main method used with run-flat tires (which are designed to resist puncture and allow the car to be driven a good number of kilometers like that) due to the nature of these tires not being tolerant to internal unwanted elements (like the embedded chip of a direct TMPS, for instance).
But the accuracy of such methods lags behind that of the direct TPMS. These are sensibly more expensive and are rather to be found in more expensive cars, too. They are built around embedded sensors mounted inside the tire and are more reliable and more accurate.
So much about the advantages of the direct method! The disadvantage is not only the increased cost of the system itself, but also the carmakers’ cost of assembling them inside the tire. Continental, one of the suppliers of such systems is at a clear advantage compared against its competitors, as it is also a major supplier of tires, being, therefore able to offer a complete solution to its customers (tire + TPMS). The information about all four tires (sometimes five, when the spare is included) is sent by the electronics around the sensor (and inside the tire itself) through a wireless method and is then displayed on the instrument cluster under board computer control. As a bonus, direct TPMS systems also monitor the temperature inside a tire and can account that for every tire individually.
Besides the cost, the main disadvantage of direct TPMS is the battery required to power each sensor inside the tire; not only does it have a limited life (sometimes you have to change the tire because the TPMS battery has depleted!) batteries do not perform well in various harsh climatic environments (do not forget, the main battery in a car is still lead acid battery, but you cannot put one like that inside the tire). To overcome this advantage, some companies invest in research for getting battery-less TPMS systems on the market. One option at the moment is a method based on the Surface Acoustic Wave technology (also known as SAW); another option would be to use electromagnetic cross-coupling to eliminate the batteries of a conventional system. Also some theorists look into using energy harvesting devices for the same purpose.
The advantages of the direct method are prone to make it the method of the future, as designers are confident in the expanded possibilities of the embedded sensor chip. The current economic climate is the only thing still driving the indirect method, as the solution can cost as low as less than half price from the direct method. Its accuracy makes it not only undesired by car manufacturers, but also illegal in the US only (with a few exceptions).
Browsing the history of TPMS, one can conclude they were rather slow to come into cars due to the reluctance of end users to pay for it, due to the split investment in both existing methods (direct and indirect) which ended up making both of them not as cheap as they could have been, and due to the unreliability of the early versions. They will, however, be on the cars in the future due to legal reasons, safety reasons and environmental reasons.
Many semiconductor manufacturers (for example Freescale) support design of such systems providing almost off-the shelf solutions for designers.
Read the Italian version: Metodi per controllare la pressione degli pneumatici
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Smart Car?
I hate my computer tries to think for me cause it guesses wrong most of the time. So I do not think i want my car to be to smart
so you want a stupid car?
so you want a stupid car?
Snow Tires
As someone that lives in a temperate climate (Canada), what bugs we is needing to swap the senors (or have 2 sets) when changing from snow to summer tires and vice versa. With my Toyota a hefty fee is involved to swap rims and sensors or reprogram to new sensors. I just put up with the flashing light for the winter.....
TPS memory deficit impacting winter tire swapping is bogus
This is discrimination against snow-country people and an economic burden for folks like me who are on disability and a very tight fixed income below the poverty level. All the auto manufacturers had to do, if they were so worried about the costs of this now-mandated equipment and "our convenience" as customers (not on your life) was to make sure the system's memory chip had enough memory capacity to store information about TWO sets of rims or tire information or make it a snow-country option and let the owners decide if they were willing to pay for their convenience or forego it---problem solved regarding the necessary seasonal tire-swapping snow-country folks have to bear up under every change of seasons. If one then has the option and the monies to forego upgrading their tire pressure sensor system to allow for monitoring two sets of tires, one still has auto industry employees who can stay busy working and doing a job and earning a wage swapping out the tires and rims and recalibrating the sensor system for the different sets of tires changed out seasonally. There's honestly and humanely no need to make it an economic or convenience burden on the general public by any stretch of the imagination. The auto manufacturers do not worry about price increases which they simply pass onto us, protecting their interests and avoiding any possible legal liabilities---at our expense---the point is to break down our spirits through inconveniences and needless expenditures on the road to bankruptcy. They've already added $200-$350 cost to vehicle selling prices for these tire pressure sensor devices, depending on the vehicle, to all new automobiles 2008 and after by mandating these tire pressure sensor systems on all autos---true, safety is a valid concern as is fuel economy, sure, but this ain't no Disneyland. People do get in car wrecks, sometimes through equipment failure due to negligence, people forget, people get buried under and distracted by the day-to-day activities of life---that's life! This does not give our governments' employees free reign to start MANDATING to US, THE EMPLOYERS, THE BOSSES, about "how it's supposed to be, WILL BE (or face hefty fines and/or imprisonment" for---crimminy---failing to check my tire pressures regularly (I've been doing this regularly as a matter of course since I was 16 back in 1971 when I first got my driver's license, plus I am the son of an engineer, but not everyone is as blessed with knowing the importance of this as I am). If one is supposed to be doing this as a matter of course as a driver then for God's sakes please teach it in the drivers education classes as a mandated, must-be-done part of the drivers' responsibility, not beat us over the head with and use it as a means of "catching" us being "bad" after the fact for some twisted, sick, psychotic, psy-op agendas and mass-mind manipulations of public opinion which is what this backdoor oppression and tyranny is, slipping in disguised under the guise of "doing good" and/or under, wrapped in, behind the "banner of benevolence"---typical methods of wearing down the populace into semi-trusting complacency and selling us a hidden totalitarian and tyrannical agenda bent on total world peoples' thoughts, actions, and spirit domination, I will add---all for the conveniences and greed of the corporations (and ourselves) and their insatiable lust for some "real" or delusional (and this is REALLY what it is, if we reap what we sow, and we DO) "power" of a master-slave construct. Ultimately, they are trying to mold us into ideal buying machines who will take what we get and "love" it. Sorry about the politics but this is the root of the problem as I see it, and a viable solution to the cost and inconvenience problems with these now-mandated tire pressure monitoring systems as presented to the general public for use.
RE: TPS memory deficit impacting winter tire swapping is bogus
Hi Bob,
I am sorry Bob, but discrimination is a word I completely dislike, because it tends to be used more and more and without a real background. There is no discrimination when somebody sells you something. If you do not like it, then you do not buy it. It is not mandatory for anybody to have a car. The world has been living for milenia on Earth without such features.
Besides, cars are not sold for disabled pople. Not in particular, I mean. They are sold for whoever wants to buy them. I agree that government regulation for making TPMS mandatory on cars is out of line, but most government regulations are too (like the one imposing on small shopowners to have a ramp for disabled chairs; the price of this ramp is reflected o the merchant's pokect, who transfers the cost to normal people who buy from the shop; why should normal people pay for the handicapated ones? is this not also discrimination?)
Regards,
Cristian
My experience as a employee
My experience as a employee at a tire store in the northwest of washington has led me to the opinion that these tpms systems are a huge waste of time, they slow down the work done on tires and wheels plus they are very costly, and they are permanent meaning if you dont want them then too bad cause your car will continually bitch about it until they're back.
I hate these things
i just recently learned that
i just recently learned that u can disable the system on most cars, for anyone that has it and hates it
If you hate these things,
If you hate these things, you hate your life!
Too picky
My new nissan versa has these and they are far too touchy. When my tire pressure drops from 35 psi to 33 or 32 the annoying light comes on and stays on till i fill them. Not only is this annoying for 1 or 2 psi but it doesn't take into account that i like to have my tires slightly low in the winter for better traction in the snow. Good idea, but technology needs to be improved
They're a pain to have on your car
Most of these systems use batteries, they're big and heavy, break and the people installing tires
break them when fitting new tires. Once they do get the new tire on they need to re-program stuff
to get them to work. It's a pain, but I saw an easier way.
From http://en.wikipedia.org/wiki/Tire_pressure_monitoring_system
"Lastly, the most recent advance with TPMS technology is the introduction of Battery-less Direct sensor systems which require zero maintenance and are very reliable. [[VisiTyre])[4]] is the first of this new class of battery-less TPMS which allows pressure on demand readings immediately from ignition and unlike radio frequency TPMS systems is also transparent to all tire construction types."
If we are going to be forced to have these things on our cars at least give us a system that works.
tpms is a big pain in the
tpms is a big pain in the ass, especialy if u do ur own work on ur car, such as rotate ur tires, cause then u need to buy a book that tells ur how to configure the system cause it gets all confused when u do that and flips out, and its just another feature that isnt needed if people wernt so lazy that if it goes haywire, costs an arm, leg, and ur left nut to replace
interesting fix
There is a way to trick the car to think the sensors are fine... i have a lexus is250 (2008) and when i put a cheap set of rims on my car which do not allow TPMS sensors all i had to do was build a small pipe bomb type thingy which has air pressure inside and put all 4 tpms monitors inside of it, then i put it in my trunk and now my car thinks that the tires are fine! So even if you do have this.. which really is pretty cool when you live in a climate that doesnt change much.. you can always do a hack to fix your problems. Unless you are a moron who doesnt like to put something under a table leg when the table gets rocky then you can def fix any issue you have, not to mention it worked great for me when i had the stock wheels on... stop being a moron and either fix it or dont buy a car with it... stop finding reasons to feel like you are cornered when you arent, and if you have to feel special because you can get mad at something you have no control over then go get therapy... you are the type of person who ruins it for the rest of us, like people that call in saying they are offended by something on TV, JUST DONT WATCH TV! STOP RUINING EVERYTHING FOR PEOPLE WHO LIKE IT! DOOOSH!
Interesting comment from Reddit
"I work on automotive computers. TPMS is a big deal right now (I'm in the US where TPMS is already law).
The direct read system (which is what most cars have) has a transmitter in the valve stem. The battery is good for 7 years. Tires need to be replaced at least every 7 years. UV from the sun, and chemicals in the air breaks down rubber, so even if the tire hasn't been used much you still need to replace the tire.
The transmitter send an ID along with the tire pressure (and temperature in some cases). There is a motion sensor so the pressure is only sent when the car is moving (I'm not sure how this works). This ID is typically 8 hex digits, but some are only 7. (there may be others as well, but that is all I've seen and I've seen a lot of different TPMS systems) It is important to get the correct sender for your car - there are several different radio frequencies used (and I presume data formats, but I haven't tried to read that)
The module that reads your remote door lock is generally tasked with reading the signal from these senders. It has a radio anyway, and connection to the cars network, so it is just a small amount of code to deal with the TPMS.
There are three ways for the car to know what sensor IDs it has.
The least common on is the car just reads all sensor IDs - eventually it will discover that 4 (5 with spare) ids come up more often and assume those are its tires. This works, but I think you can see why it isn't common.
The rest require the user to program the ID into the computer by one of 2 procedures. This is greatly preferred, because then the car knows which tire has which id. However you need a scan tool to enter this ID, and only the more expensive tools have that ability. You also need the scan tool to update the mappings each time you rotate the tires! At least one manufacture is using encryption on the sensor id programing procedure so you have to have a dealer program these IDs (I know you are curious, but I'm not allowed to tell you who - my company does other work for them and if I ran them down they might drop us as a supplier and then I get into trouble).
Some cars have you use a scan tool to enter the IDs, using a keypad. The IDs are stamped onto the back of the senders. When you put the tire on the rim make sure you write this number down so you can enter it into the computer after you have the tire on the car. There might be a different procedure to rotate the tires, or you might have to read the sensor IDs, and then re-enter them for the correct tires.
Most common is the scan tool just tells the computer to activate programming mode. Then you walk around the car and activate each sensor in order (normally LF-RF-RR-LR-spare). Sometimes a magnet on the valve stem is all you need to activate the sensor. (those cars generally include the magnet in the tool kit and have a button you push to enter tire registration mode so you don't need a scan tool). Other cars require you to have a TPMS activation tool that somehow tells the sensor to activate (these tools eat batteries so I assume they are mostly an electro-magnet, but a normal magnet doesn't work so they must do something else). In any case once the sensor activates the horn sounds and you move to the next tire until done.
Some cars allow 2 sets of sensors so you can have summer and winter tires. This is not very common though, which is why others are complaining about the warning light being on all winter (or some trick to get around that).
I know nothing about the indirect systems. I don't have anything to do with their programming.
I hope this is more detail than you wanted to know."
bluGill from REDDIT
New Patented Batteryless Device for TPMS
Dear Sirs
Good greetings to you !
We are pleased to announce our update New Batteryless Device.Because batteries limits operation life time, create maintenance and disposal issues . Vehicle manufacturers are also concerned about costly warranty claims and litigation that may result if injury and loss of property occur as a consequence of RF based TPMS battery failures. The most recent advance with TPMS technology is the introduction of Battery-less Direct sensor systems which require zero maintenance and are very reliable.
After few months researching & developing, I have succeeded our Invention Product-Batteryless Device.It measures 16 mm in diameter by 32 mm length.and the weight is just 6.6 g . The principles is the coil fixed and magnet vibrating by spring. It will generate the DC 3V & 600 uA current easily while the vehicle is moving. It will not influence by centrifugal force. The Batteryless Device and 433.92 MHz transmitter install into the current valve-stem type TPMS which fitted on the wheel,after few turn,it is fast to generate DC 3V to power the transmitter sending the signal to display .Attached is the photo of Batteryless Device for your reference.
There will have the following advantages to use my Invention Batteryless Device.
1. It is battery-free . It consumes no power and there are no
batteries to run low, leak or expire. This means less cost, higher
reliability and less maintenance.
2 This Device is small and lightweight. At only 6.6 grams and Dia.16 mm x L. 32 mm to be fitted your current TPMS by little modifying the housing.
3. It’s 10 years warrant to create zero-maintenance for your TPMS.
4.The most fast device in the world to generate the DC 3 V & 600uA while the vehicle is running a few minutes .. And working at the critical temperature -40° +125°C
5.Cost reduction. It costs only FOB Taiwan US$2.95 per piece. Mini order 10,000 pieces.
6.Your product will become “Green”TPMS.
The samples are available now, I appreciate your company being able to evaluate our New Batteryless Device. If you need a sample to test, please email me .
Thank you very much for your assistance.
Yours truly
Jack HF Wang ,CEO
Tyresonic,Inc.
California,USA
Battery less TPMS
Dear Sir,
We are from India .We would be interested in your product .Please send me the details about your product,So that we can procced further .Please quote me the price for your sample also .
With Warm Regards
Mahesh Rao.
Please advise the email address to contact you
Dear Mr. Wang,
Please advise the email address to contact you.
I would like to check your solution.
Regards
WILY
Hello sir...Our Company
Hello sir...Our Company would be interested in the Product.. Would be great if i could have an email address or some way of contacting you..
Thank you
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I believe
Dear Honer,
I believe in i want to suggestion in your parts so pls send me quotations to part no and prize in my email id
Tire Monitoring
thanks for this article.. yeah you are right that tires are the most vital elements of a car.. Incorrectly tires installation would produce road accidents and low pressure tires would harm environment, so we must be assure that we need to monitor our tire pressure..this is good idea, i will surely share this to my friends..
the source, please!
Hello Cristian,
In this article, you said:
"There are extensive studies conducted both by various European Safety Authorities or by TPMS supplier companies (obviously in a bid to convince the carmakers that what they sell is needed) showing various figures of accidents caused by incorrect tire pressure (in France, for instance, these studies claim that almost 10% of road accidents could have been averted by having the tires correctly inflated)."
Would you, please, give us the source whence you found that in France 10% of road accidents could have been averted by having the tires correctly inflated?
Thank you!
RE: the source, please!
Hi Ionela,
The "10%" figure is extracted from an internal document of the company I was working for at the time. It was a study which gathered figures regarding this kind of accidents across Europe but I only took into account the relevant number for France because this was the highest. The very reason for conducting the study was to understand the fesability of developing a business in that direction (and this eventually happened). However, as you might understand, it was an internal document and I am not allowed to disclose its full content.
Regards,
Cristian