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TPMS is pathetic AND REALLY NEEDS AN UPDATE TESLA!!!

TPMS is pathetic AND REALLY NEEDS AN UPDATE TESLA!!!

I know this has been discussed before, but I'm upset that Tesla has not addressed this problem yet. Yesterday morning it was extra cold here in Salt Lake City. It was around 42 and raining. About a mile from my office, the low tire pressure warning comes on. I'm in rush hour traffic, and it is pouring rain, and I'm in "office attire." In my POS 8 year old Suburban, or in my slightly less POS 3 year old Jeep, it would tell me the exact tire pressure of each tire. My super duper Tesla just tells me that the pressure is low somewhere. How low? Do I have a flat? Can I make it to work? Am I going to destroy a tire if I keep driving? Do I have to stop in the pouring rain, get out my tire pressure sensor, and check each corner (as I get wet, dirty, and hopefully not killed by a passing car as I squat and check the driver's side tires), or do I chance it and drive the last mile on a potentially flat tire so I can safely check at my parking garage? I decide I can't stop in the pouring rain, in traffic, and I keep driving with the feeling of panic in my body. I get to the garage, and check each tire. The fronts had dropped just 1 psi below the label on the door, and that triggered the warning. THIS IS PATHETIC! THIS IS UNSAFE!!! I could have stopped in the rain, and been killed checking a tire that was just barely low because of the cold temperature, when I should be able to look on the touch screen and see what the pressure is for each tire without getting out of my $112,000 car and putting a stupid gauge on each tire to do it!!!!

P.S. - Otherwise I continue to love this car and couldn't be happier, but the TPMS problem is a big one.

TeslaTap.com | May 10, 2014

This has been high on the desired features list for over a year. You can add you vote at: http://teslatap.com/questions/tire-pressure-values-and-locations/

With the current design it's unlikely we'll ever get which tire has which pressure, but showing the pressures would go a long way and should be doable with just a software update.

Captain_Zap | May 10, 2014

Did the warning tell you to pull off the road safely? When I had a screw in my tire, the warning that told me to pull off the road safely didn't occur until my tire was getting close to 25#. That detail makes me wonder if you had just a general TMPS warning to alert you that the TMPS had an error.

I used to get general warnings on occasion immediately after an update. But, the general warning hasn't happened in over a year.

chenglo1 | May 10, 2014

Teslatap ur post doesnt make sense. Please clarify. Software can show pressures but just not at which wheel?

rdalcanto | May 10, 2014

@ Captain_Zap
Are you saying there are two different warnings? One for slightly low pressure and one for really low pressure that tells you to pull over? If true, that would already be much better. One warning to tell you to add a little air, and a different one if you are so low you need to stop. Need to check the manual again....

LEvans | May 10, 2014

Doesn't the TPMS transmit the exact pressure of each tire to the car?

rdalcanto | May 10, 2014

Not that we can see....

RanjitC | May 10, 2014

@rdalcanto I have seen three warnings. Tire pressure low, Tire pressure very low (I think this indicates a flat) and tire pressure extremely low pull over safely. This happened as I drove to the tire shop.

TeslaTap.com | May 10, 2014

The technical issue is the TPMS does send the pressure of each wheel to a single antenna that mounted near the propulsion motor. Each TPMS as a unique code to identify it, but the system has no way to know which TPMS is associated with which tire location.

GM had a clever system where after a tire rotation you told the system which sensor was in which location. I think you had to drop the pressure in each tire and then inflate it in a specific order. I'm sure service and wheel places hated it (time consuming), and could be easy to get it wrong.

Some cars like my Lexus LS460 would show the tire pressures for five tires (spare included) but not which pressure goes to which tire. Tesla could implement a similar system fairly easily (better than nothing) with only a software update.

Some manufacturers include a TPMS antenna near each tire so they can identify the pressure with a specific location. This system is more costly, so is not as often used (although the best). Tesla does not use this system, and is why I don't expect to see tire pressures by location on my MS anytime soon.

That's not to say Tesla couldn't make some way to tell it which tire is with which sensor (with the current hardware), but it would be a bit of a kluge like the GM system (and GM may have a patent preventing others from doing it).

AmpedRealtor | May 10, 2014

In order for you to receive a TPMS warning, the software needs to know the starting tire pressure, current tire pressure, calculate the difference, and if outside of a certain threshold a warning is issued. The numbers are known to the software, it would seem, just not displayed to us in the UI. I agree that this is needed. My 2010 Highlander gives me tire pressure for each tire.

TeslaTap.com | May 10, 2014

@RanjitC - Also has a warning: Tire Pressure Too High, which I've seen when the pressure is above 50-55 psi

TeslaTap.com | May 10, 2014

@AmpedRealtor - While I don't know the specific engineering, I'd be surprised if it needs the starting tire pressure. I assume it just needs the current tire pressure (and temp) and from that always knows if the tire is properly inflated or not. For air suspension, a clever system would also compensate for the car weight (with cargo), but that may be asking too much!

Why do you thing it needs the starting pressure and to do that calculation?

RanjitC | May 10, 2014

@TT that is a good warning as most tires are only rated to 50 psi. My 911 has the most informative system that I have seen but I think the above 4 warnings should be sufficient for most people.

Jonathan D | May 10, 2014

Does the TPMS measure pressure directly? I know many are just based on variations in wheel rotation indicating decline in pressure.

Bighorn | May 10, 2014

I don't think knowing the starting pressure is part of it--the system is set at a certain alarm threshold which can be adjusted by a service tech by PSI.

My5bAby | May 10, 2014

@ OP

I'm a Fanboi and get tired of people complaining about little things or things that Tesla cannot control.

HOWEVER, YOU MAKE AN EXCELLENT POINT !

Even without displaying which tire, it should be possible to calculate if the pressure is dangerously low. While the car will recommend pulling over if you should stop immediately, there is a difference between needing to do that and being able to safely continue City driving to get to work, Home or to check the pressure. At a minimum there could be 3 messages, Pull over immediately, Tire pressure low please check ASAP do not exceed 40mph, Tire Pressure Low please check ASAP.

Personally I only had Tire pressure warning twice. Once resolved after stopping and turning off the vehicle, the other resolved before I stopped.

Thank you

NKYTA | May 10, 2014

My5bAby, how many miles now?
:-)

LEvans | May 10, 2014

@TeslaTap: Wow, thanks for the really useful information about how the system works. Really it's so easy to do an inflate and reflate by 10 PSI of the 4 tired. Would likely take just 2 minutes. Maybe this would be a good option for Tesla and they can include coding the location as part of the annual "service visit" thereby adding more value to that service.

michael1800 | May 10, 2014

Do the low, very low, extremely low messages work for you (honest question, not sarcasm)? Knowing that might have made the situation less anxiety invoking. A non-very/extremely low message along with your noted recent temperature drop reveal the severity of the situation (not severe). The 1 PSI difference you noted was likely due to heat expansion after your drive. The cold tire pressure was likely 5+ psi off recommended.

I'm not saying I prefer having the current system rather than knowing the actual pressure numbers. I nearly always prefer to have more/raw data rather than 'dumbed down' data. However, I don't find the current system pathetic or horrible. It works well. If a tire is just low, I get notified such and top them all off. If a tire is going flat, I get notified such and don't have any problem finding which one is flat (I've only had one flat in the MS and it was due to special circumstances).

LEvans | May 10, 2014

Come to think of it my dad's Acura lists the pressure at each wheel. Maybe Tesla could use something similar?

johngratcliff | May 10, 2014

It would be more convenient if the TPMS provided the pressure by psi and the location of each tire. I do not know whether both of those things are possible with the current hardware simply by adjusting the software. And I do not know how difficult or expensive it would be to upgrade and retrofit the hardware if that is necessary.

What I do with some regularity is check the tire pressure in the morning. I do this once a week, when there is a dramatic change in temperature, and when I am traveling. Except for washing the car it is about the only maintenance the car requires.

Recently, while traveling through Mississippi, I forgot to check the air pressure before I left Jackson headed south. About 25 miles out I got the low pressure warning. It was a beautiful day and I pulled over to check the tires. Three were at 47 psi, but the front left was at 37 psi. I pumped it up to 47 (on my P85 the cold tire pressure is to be 45 psi, which goes up as the tire warms up)and continued to Magee, MS, and contacted Tesla's 24/7 roadside assistance. I had noticed that the pin inside the valve stem on the subject tire was loose and mentioned that to the roadside assistance technician and asked him to call ahead to my destination, Laurel, to locate a Goodyear dealer and provide me with its address and let the dealer know that I would be there in about an hour. He did. I drove on to Laurel, went to the dealership, had the stem repaired, and was charged nothing. The dealer said seeing the car and finding out about it was enough for him. Mind you, fixing the stem is not an expensive service of course.

I don't want to minimize the inconvenience of the TPSM problem that is the subject of this thread, but I have the following attitude: We are in the adventure stage of Tesla, at least in the deep South. It won't be long before superchargers and service centers are everywhere and owning and operating a Tesla becomes comparatively boring. As my friend and fellow owner Ed Benson from Foley, AL, says, "It is like driving a Model T years ago looking for a hardware store that can sell me a can of gasoline." If you get to Foley, stop by Ed's appliance store for a free HPWC charge.

TeslaTap.com | May 10, 2014

Expanding my knowledge a bit, it appears in the US, NHTSA does not require TPMS temperature compensation (at least when it was first required for all cars). I couldn't find any change to that law since enacted around 2001.

From at least one manufacturer, they do include temperature monitoring so it can be compensated (which makes sense). No idea if Tesla uses temperature compensation or not, but my best guess is they do.

I did dig up there there is very clever way software may be able to automatically identify which sensor is related to which tire position. Since the car has ABS and monitors each tire's rotation, it's proposed that software can detect tiny differences in rotational speed of each tire and correlate it with the TPMS's rotational information as the two should match up perfectly. For example, going around a curve the outside tires rotate faster than the inside tires.

For a lot more engineering details of TPMS sensors, electronics, I found this interesting current article (from the UK): http://www.swindonsilicon.co.uk/wp-content/uploads/2010/07/TPMS-Past-Pre...

rdalcanto | May 10, 2014

I checked the manual, and it doesn't mention anything that I could find on different messages depending on the severity of pressure loss. It does say that when you add air, you have to drive for up to 10 minutes for the warning to go away. I was going to do an experiment and take air out at 5 psi increments to see if the message changed, but I don't want to drive around on low pressure for extended periods if the message isn't immediate....

rdalcanto | May 10, 2014

Forgot to add, I doubt Tesla uses temperature compensation. If they did, I don't think I would have gotten the message yesterday morning.

sule | May 10, 2014

Just a few comments, some could be viewed as questions:

1. Temperature compensation? When temperature rises so will the pressure... and vice versa: PV=nkT (pressure times volume is directly proportional to temperature when nk is const). Thus, if what is important is the pressure then pressure sensors will do just that and no "compensation" is needed. Volume may also change somewhat as may softness of the tire, but it would be in the same direction, so it may work out well - just maintain pressure.

2. Even if "compensation" is needed, the car has air temperature sensor at the very least. This is a very good approximation of tire temperature at the start of day, although not while driving or shortly thereafter.

3. Pressure while driving may vary wildly. Not sure, but as you are flying over potholes or hitting bumps it will go up and down - the tire is the first part of the shock absorber too. This may be too crazy to mean anything beyond low / very low / extremely low. In essence, target/desired pressures are meaningful only to tires on cars that are not in motion. Tires not in use (e.g. spare) will have lower pressures as there is no vehicle pressing down on them.

4. Since each sensor has to be registered separately, it can be read separately too. And it would be useful to indicate at the very least which one is the problem... while there is a minute chance this isn't doable in software only, there is a huge chance that it is.

Pungoteague_Dave | May 10, 2014

My BMW motorcycles can give me real time readouts of each tire's pressure, compensated for ambient temps, so the pressure isn't the real internal pressure, but an adjusted temp that reflects cold tire pressure at rest at some specific level (68 degrees F IIRC). That way it helps a driver get the pressure right no matter what the current weather conditions or how long the car has been driven, tire friction heat, etc. So it can be done well.

Roamer@AZ USA | May 10, 2014

@ sule, smart tire systems have been providing tire presure, temperature and variance from set point based on tire air volume charts that allow you to know how many psi the tire is above or below the desired set point across the entire range of tire temperatures. I have used the system for years on my tow vehicles and trailer tires. To bad they quit selling the system to the public a few years ago.

All of this is possible with simple software. With smart tire you select a tire position then let a few psi out of the tire and the computer then matches that tire sensor to a position. It's pretty simple. I imagine Tesla has a long list of things like this they just have not had time and manpower to program. If they worked with app developers like Apple has done they could harness worldwide talent to create these systems faster and maybe even with more creativity. Someday it will happen. Lots to do.

Roamer@AZ USA | May 10, 2014

With smart tire I can monitor six tires on my tow vehicle and 6 tires on my boat trailer all on the same small display monitor. This is not new technology. It's been around long before DOT required all cars to have a presure monitoring system. Ironically the DOT rule on passenger cars killed smart tires automotive product line.

http://www.smartire.com/products

tga | May 11, 2014

The GM system is easy, even for DIY tire rotations:

Press and hold two buttons on the remote until the car beeps.
Go to the first tire, raise or lower pressure until the horn beeps.
Repeat for remaining 3 tires.

I think the order is start at driver front, work CCW around the car.

Requiring a trip to the SC to do this (especially when changing to winter tires) is pathetic. There is no reason Tesla couldn't do something similar. The current system is just to lock you into Tesla service.

And just display the actual pressure. Obfuscating it behind generic messages is equally pathetic. More information is always better.

drax7 | May 11, 2014

The lady doth protest too much methinks, Shakespeare , hamlet 1602

You need at least two readings per tire, just to be super sure,
or you are risking your life.
Your entire life.

Be extra sure.

jordanrichard | May 11, 2014

What on earth did you guys/gals ever do when driving cars made before 2007?

TPMS is not a "feature" that the car companies wanted to put on the cars, it was mandated by law. This all stemmed from the fiasco with blowouts with Firestone tires.

I have 2400 miles on my car and I have had only 1 tire pressure warning and it was oddly about the tire pressure being too high. This was after being on the highway for 45 mins. The warning disappeared after about 2 mins.

All these features that most people call "safety related items", is really laziness related items. We as a society have become Pavlov's dog. We see a warning or hear chime from the car, we immediately reacted, without taking a moment to think. There were many times when I had a Ford that the "check engine" light came on. Most people would panic and run to the dealer. Well if one read the owner's manual, it says that it just means there is an emissions related item out of whack. To me, as long as the engine was still running fine, then all was good.

The main concern with low pressure in a tire is if it is in one of the front tires. Should the tire pressure get so low that the tire shreds it's self, then you will have a steering/control problem. However, if the pressure is getting that low, you will feel the car pulling in one direction. This should prompt you see what the issue is. So, check your tires pressures regularly, and pay attention to how the car feels.

cadethoerk | May 11, 2014

If the single antenna is placed as to maximize the biggest distance delta from each tire then you could calculate the time it take to get a signal from each tire and locate it.
Just a thought.

rdalcanto | May 11, 2014

@jordanrichard
That is just the thing. After I saw the warning, I could have sworn the car felt funny (placebo affect). Without a TPMS system, I would have just been driving happily, and checked tire pressures at a safe, convenient time as part of general maintenance. But when you suddenly get a warning, you feel obligated to stop and check. In my case it was in rush hour traffic in pouring rain. People are hit (including highway patrol) all the time when standing next to or working on a stopped vehicle. The point is the pressure wasn't that low, and this needless message without more data almost got me to pull over in the rain, get wet and dirty, and possibly hit by another car FOR NOTHING!

LEvans | May 11, 2014

@jordanrichard: This whole attitude of what on earth did you do before you had xyz is getting a bit tiring :) The fact is apart from people who read this forum and are fond of the brand, these cars need to appeal to and work flawlessly for a majority of other potential customers in the market segment without issues.

Most people would be quite annoyed, as the OP was, to be told of a tire inflation issue with no information about which wheel it is and how severe the loss of tire pressure is. I know I would be if I was traveling someplace in bad weather.

Virtually every car manufacturer has figured out a way to list the tire pressure at each wheel. Tesla should do the same. This is a legitimate issue.

jordanrichard | May 11, 2014

I guess my remarks come from seeing people quickly forget how to do things on their own. People are just becoming too dependent of bells and whistles and forgetting how to do things as I said, on their own.

I and this may be surprising in light of my remarks, agree that a TPMS should be able to tell you which tire is running low. Though perhaps the way Tesla is looking at it, regardless of which tire it is, you are going to need to stop and check anyways. It certainly would save one time, if one knew which tire to check.

TI Sailor | May 11, 2014

+1 rdalcanto
+1 cadethoerk

wholland | May 11, 2014

I had a similar thing happen to me traveling to work. I had 22K miles on my original 21 inch Contis. Driver side rear tire actually ruptured with a 2 inch split. I felt nothing while driving over 70 mph (morning commute in So. Cal. :)). First, a low pressure warning came on, which I've seen several times in the past and pretty much ignore. Shortly after this warning another warning told me that pressure was "extremely low" and to pull over safely. I did so to find a tire that was completely flat with a large split. Therefore, the system does warn you when a tire is flat and you need to pull over. It doesn't tell which tire is flat, however a simple look gives that info immediately. Bottom line: with low pressure warning only, I would continue driving until checking pressure is convenient and safe.

George with SacEV | May 11, 2014

Totally agree with the OP. Come on Tesla bowfins, this should not be that hard.

Pungoteague_Dave | May 11, 2014

@jordanrichard: the issue is that the technology of tires has changed. In the old days, there was no way to drive a car with a flat tire without damaging the rim. When pressures were low, you KNEW it immediately. When it was flat, you had to stop. Modern tires have far stiffer construction and a flat tire can now be represented by only a small change in handling, imperceptible to many. Tires on older cars had obvious bulges when low on pressure, but today many tires with low pressure show no signs of low pressure on visual inspection. That's why TPMS were mandated - it is a necessity with the latest tire technology. Initially, it was for runflats, but is now required on all cars because many tires can be run when flat, at least for short distances. Same for motorcycle tires, but even more critical. The world has changed along with tire technology. I use the TPMS systems on my bikes to check status, every single time I ride. Besides being a convenience, it has helped me get off the road twice when a flat was happening - critical on a motorcycle because flats can be fatal. Progress is a good thing.

jcaspar1 | May 11, 2014

jordanrichard +1

I think a system where you have to lower and raise the pressure of tire to identify it is going to be too much for many owners.

_thierrY | May 12, 2014

Individual tire pressure monitor would be a « nice-to ». I have it in my “good-old” chevy Volt ;-)

However, I don’t feel it’s dramatic that I don’t have it in my MS. Having a severe flat will impact car’s behavior anyway so I’ll notice it… especially if I previously received a warning. If it’s not safe or convenient to stop, I’ll just slow down and pay more attention to car behavior until it’s possible to stop safely and conveniently.

I also like to “inspect” tires by kicking into them… It’s totaly useless but funny.

@sule

"3. Pressure while driving may vary wildly. Not sure, but as you are flying over potholes or hitting bumps it will go up and down - the tire is the first part of the shock absorber too. This may be too crazy to mean anything beyond low / very low / extremely low. In essence, target/desired pressures are meaningful only to tires on cars that are not in motion. Tires not in use (e.g. spare) will have lower pressures as there is no vehicle pressing down on them."

This is not true : pressure is not a function of the weight on the tire. As you pointed out, PV=nkT. That is P=nkT/V. In a no-leaking tire n, k is constant. Variation of volume is negligible because when tire is compressed at one point, the tire expands at an other point. That's all a tire is about! Without this behaviour, air-tire would be useless and we would use hard wheels...

So pressure is [almost] only function of temperature... and quantity of air within the tire (n).

Rocky_H | May 12, 2014

@_thierrY, you are getting some of that wrong. Weight on the tire does definitely affect the pressure. You say that variation of volume is negligible, but that's not really true. Have you ever popped bubbles in bubble wrap packing material? That's this same principle. You say that if you press on the tire at one point, it will expand at another point, but tire rubber is not infinitely elastic. It resists being stretched at some point. Back to the bubble wrap analogy, if you first touch the bubbles, they seem soft and squishy with low pressure in them, but if you press on them harder, they get tight. You are attempting to reduce the volume, but it has ramped up the pressure because the plastic is resisting stretching anymore. Keep pressing harder, trying to push the volume down to nothing, and the pressure eventually gets high enough, it blows out of the plastic wall, which couldn't stretch any more.

J.T. | May 12, 2014

@Rocky H Does that mean that the spare I recklessly carry around in my frunk that is filled to 45 psi will be overinflated when I put it on the car?

carlk | May 12, 2014

Porsche's TPMS has a learn mode that somehow detects the position of each tires automatically. You don't need to manually tell the system which is which.

_thierrY | May 12, 2014

@Rocky_H : comparing behavior of a tire with bubbles wrapping is kinda risky... But if you don't believe me, just try it :
1- Take tire pressure.
2- Jack the car so the tire does not touch the ground.
3- Take tire pressure again....

@J.T. ;-)

Alex K | May 12, 2014

@carlk | MAY 12, 2014: Porsche's TPMS has a learn mode that somehow detects the position of each tires automatically. You don't need to manually tell the system which is which.

Porsche uses sensors at each wheel well. There is no "learning" per se needed.

bb0tin | May 12, 2014

I can see that listing each tire pressure could be an issue depending on the hardware setup. However, aren't you really only interested in the lowest or highest pressure that triggered the warning, and whether it is changing. Tesla should (easily) be able to change the warning to include a single pressure number. Eg: 'low tyre pressure 28psi'. If it then changes to 'low tyre pressure 25 psi' you know you have a problem.

carlk | May 12, 2014

@Alex K I did have to reset mine once after getting new tires from Costco. Usually there is no need to rotate the tires but it turns out Costco switched my left and right rear wheels and messed up the system. It took the system a couple minutes to re-recognize each tires. I actually did not even know about this TPMS reset function buried inside the control menu until this problem happened.

Rocky_H | May 12, 2014

@_thierrY, Hmm, perhaps you are right, and I may try that experiment, but I would think that generally pressing on a tire would be compressing its volume somewhat.

Rocky_H | May 12, 2014

I did some more research on this, and thanks, both of you. I just learned something. My principle was correct, but tires are made to be very structural and be so tough that they heartily resist volume changes, so my analogy of some other thing having its volume compressed when you press on it doesn't apply to tires. So I did find a couple sources say it's technically true, where a tire's pressure will go up some, but it's such a small percentage it's generally not measurable on a tire gauge.

renwo S alset | May 12, 2014

Yeah, we definitely need TPMS for each tire and where's the damn dipstick, too?