h4ldol

I searched and only found 2 threads about TPMS and neither were really helpful.

So, basically I would like to add TPMS to OEM 15" wheels. I have a "screw on" TPMS kit currently by Tyredog where the sensors screw onto to the valve stems but it looks pretty ridiculous and it may in the future get stolen (or taken just for the heck of it), and using the security attachment (which requires an allen wrench to remove) makes the sensors stick out even more so I don't want to use them.

Otherwise, I like the Tyredog kit and they do make a kit with internal sensors but would like to get the "best" sensors available since these would be a pain to replace if they malfunction. Ideally, it would have a small receiver with screen to monitor the pressures (rather than the ones that you can plug into a DVD receiver if you have one).

Any suggestions or experiences with various brands/models would be great, thanks!

CraigW

iTrader: (1)

I'd say just keep a close eye on pressures and glance at tires often.

Too complex to add afterwards.

h4ldol

Actually, it's really not. It's not a DIY thing for most people, but I'm sure a tire shop can install them pretty easily, and then after that the device/receiver can program all the sensors fairly easily. And it will give me comfort of mind by reducing my risk of blowing out on the freeway by driving on an underinflated tire. Checking frequently is not really convenient or helpful as it won't tell you if you have a leaking tire that occurred while driving, even if you just checked before getting in the car.

CraigW

iTrader: (1)

I checked the company out, but those sensors are huge to be spinning around atop the valve stems. Seems strange. The in tire setup looks nice (more like factory)

And love the live feed monitoring.....but modern tires (good ones) are pretty tough.

Some cars have deleted the spare lately (donut is a JOKE)

ezone

Just saw a 12 Elantra with no spare, jack, or lugwrench, and no tire pump and sealant kit either.

I guess they expect you to be able to call a tow truck at any time and place?

h4ldol

Yeah, I have the valve stem sensors and they do look fairly ridiculous when installed. Definitely an eye sore, but I keep it on for now since I've had a blowout on the freeway before and there is nothing scarier.

I like Tyredog and I'm considering their internal TPMS sensor kit but the major problem with their sensors/kits is that if one malfunctions you don't really know since the receiver will continue to display the last received value (even if it is no longer accurate at all after getting a puncture, etc.).

Our 2014 AWD Sienna also has no spare but has horrible run flat tires that are super expensive and not many tire shops even have the special equipment needed to take them off/on. Which is why I carry a tire repair kit (not the spray sh*t) and a tire inflator. I also have a donut spare that I use for longer trips.

mac25

...I work as a lube tech and a lot of people with OEM TPMS units hate them. A few customers have uninstalled them.

If you do run them run with N2 because air is a bitch with TPMS. We have a lady who comes back for a pressure check every month.

The OEM ones will freak out for being 5psi under or 5psi over.

As well make sure the TPMS sensors you get are set for the tire pressure you need. Most OEM sensors are set for 32-35psi. However, people who use aftermarket tires rated for 50psi cold always have the TPMS light on because it is set to give a warning above 35psi.

ezone

Most folks just inflate tires to spec without considering other factors.
If you want to keep the idiot light off for a long time, you have to have a grasp of some basic laws of Physics, and you have to think ahead.

And put up with yet another idiot light lit all the time, no doubt.
Why do you say this?

Only one? Lucky you.


Wait until you try to figure out our new TPMS system that has no tire pressure sensors. It's even more finicky than the system that uses real sensors.
At least now you can't break off expensive sensors when changing tires LOL.
You have this wrong. The sensors only report the tire pressures and some other data to the control unit.
The control unit decides when to turn on the idiot light.


You can't run ours low without turning on the light, but you can run ours waaaaaaaay high.
I think I noticed some GMs that turn the light on for being a little over (which I thought was a crock).

Ours won't.


There is a way to change the on/off pressure points for high performance tires on (I assume) most of the Hondas with direct monitoring TPMS.
The HDS scanner and a special code is needed.

I did this--raised the (_!_) on/off threshold-- on my own car when I switched to 18" wheels.



(_!_) <--the butt icon/low tire light

sdaidoji

iTrader: (1)

can't even imagine how they would measure without direct sensors...

LOL, it sure looks like a pressed ham

ezone

The indirect monitoring TPMS system takes advantage of sensors that are already in the car as parts of other systems (ABS/TCS/VSA).

(partially copied from another post of mine elsewhere, with adjustments)

Some manufacturers were using ABS wheel speed sensors nearly 2 decades ago to watch for large differences in wheel speeds (a low tire has a different rolling diameter than a full tire) and it would trip a "LOW TIRE" warning when it sensed a low tire, but they were not very accurate.

This takes it a few steps further, makes it much more sensitive and accurate.
Too much IMO.
It has drawbacks and limitations IMO.

This system is so sensitive it can detect a difference when the tires got rotated and trip the idiot light if one forgot to recalibrate the system.

In addition to comparing tire revolutions, my understanding here is the system takes into account data from the sensors that are used for vehicle stability control. They watch for the 'lean' and 'squirm' that happen when tire(s) go low.

The indirect system learns a 'profile' for each corner of the car, and turns on the idiot light whenever there is a significant deviation from that profile.

Ambient temperature is also monitored and factored in.

I am not a fan of this indirect system (as a tech in the trenches). Too sensitive, too finicky, too vague, and I live where the temps can change 50* or more in a week or less....that means huge changes in tire pressures.

And little to no relevant usable data on the scanner for us to "see" what the system is seeing and thinking as far as tire pressures are concerned.

I've got more gripes if anyone important cares LOL

OTOH I totally understand why the manufacturer went to this type of monitoring though, and can appreciate that.

sdaidoji

iTrader: (1)

oh, god...
the moment you put in tires that are stiffer or softer sidewalls, it will go nuts...

however, the 250 or so per sensor is also considerably high, plus the batteries dying after some 6-10 years...

ezone

Nah, but sidewall stiffness might fool it just a little.
You recalibrate with any pressure or tire changes so the system can "learn" the profiles of the tires. It can supposedly allow for seriously mismatched tires as long as it has 'learned' with them installed on the car.
Once it's learned a set of profiles it really does take some pressure loss to make the system trip the light.


On some of the cars there is a way to change calibration for different wheel sizes, but that's limited to approved accessory wheel sizes....
....So if you try to put 20" wheels on with rubber band size tires, a tire might have to go totally flat before there's enough squirm or lean to trip the light...If it comes on at all. IDK.



There are already reflashes for some of the cars because the systems are TOO sensitive.

Where'd you get that price???

2010 Civic sensor 42753-TR3-A81
$27.xx at Majestic
$9.95 athttp://www.ebay.com/itm/like/201104574765?lpid=82&chn=ps (EDIT: Oops, wrong part number there...and why did it suddenly link?)

mac25

I thought the OP was running aftermarket TPMS, I know for a fact some TPMS will display a light for High pressures as well as low.

N2 fluctuates less in temperature range than air, from external temperature fluctuations.

ezone

Sorry, I'm not buying that.
Fundamentally; air, oxygen and nitrogen will all behave exactly the same in terms of pressure change for each 10 degrees of temperature change.

Look up "Ideal Gas Law". http://scienceworld.wolfram.com/physics/IdealGasLaw.html


Excerpt from the website getnitrogen.org:

What are the effects of temperature change on my nitrogen filled tires? The pressure in nitrogen filled tires will change when the temperature changes, just as it does with air filled tires, because nitrogen and oxygen respond to changes in ambient temperature in a similar manner. For example, when your vehicle is parked it will lose a similar amount of pressure for every 10 degree change in temperature, whether the tires are filled with nitrogen or air.

All of my tires are filled with 78% Nitrogen.



Yep, but Hondas don't trip the light for too high. If they do, I haven't seen it happen yet. And I've seen some scary high tire pressures, high enough to max out the sensors.

CraigW

iTrader: (1)

Gotta love firmware updates. Now a way of life. And great for solving bugs.

mac25

ezone it looks like your right about the N2 holding the same pressure due to temperature.

However the same site, getnitrogen.org, states

"Will I have to check my tire pressures? Yes! On average, tires filled with air lose about 1.5 psi every month, whereas tires filled with nitrogen will lose that amount in about 3-4 months."

so N2 is more stable over time according to the site. It's due to the size of the molecule. O is heavier than N, but the O2 molecule is smaller than the N2 molecule.

"It is often mistakenly assumed that "molecular size" correlates
directly with "molecular weight". O2 does have a greater
molecular weight (32) than N2 (28), but O2 is actually smalle
r in size. Thus, O2 fits through the relatively tight passage
ways between polymer chains in the rubber more easily
than does N2. The difference is size between O2 and N2 is
very small, only about 0.3 times 10 to the -10th meters (0.00000000003 meters).
Among the various descriptions of the sizes of molecules,
that most applicable to transport phenomena is called the
"kinetic diameter" of molecules. The kinetic diameter is a
reflection of the smallest effective dimension of a given
molecule. It is easy to visualize that a
given molecule can have more than one di
mension, which characterizes its size,
if the molecule is not spherical. O2 and N2 are diatomic
molecules (two atoms joined by a chemical bond or bonds),
not spheres in shape but rather cylindrical in shape, akin
to the shape of a tiny jelly bean. Thus, a "length" dimension
of the cylindrical shape is a larger dimension than the smalle
r "waistline" diameter of the cy
lindrical shape. In transport
phenomena, the molecule with the smallest effective wais
tline diameter is that which behaves as the smallest
molecule, i.e., has the smallest kinetic diameter."

http://www.getnitrogen.org/pdf/graham.pdf

mac25

...not that any of this really matters in life, lol.

sdaidoji

iTrader: (1)

oh, sorry, it's cheaper for hondas then...

was using the price a friend told me of his car.

ezone

The air we breathe and pump into our tires is already 78% Nitrogen.

Ever checked the purity of a tire sample after 'filling' with N2? It isn't all that impressive.


We don't pump pure O2 into our tires, and the molecular size argument is of little value...A difference of 0.00000000003 meters? Seriously.. The weather changes faster than molecules leak.

Hell, according to their theory, they make it sound like only the Oxygen is going to leak out.......seems like the only thing left inside a low tire should pure Nitrogen! MIND BLOWN?!?

They don't talk about the other 2% of stuff that makes up the air we breathe either.

Right.


Here's what matters IMO:

The general public doesn't give a rats *** about the differences in the rate of molecular leakage -----when the idiot light comes on AGAIN and again and again and are told.... (what?? some BS reason, whatever it may be)

Some of them start to suspect they were scammed into paying $10 per tire for PLAIN OLD AIR!!!!!
You were supposed to fill the tires with this magic fairy gas that somehow keeps the tires aired up under all conditions, but you didn't...YOU CHEATED THEM!! They have been duped!!!
Now they are gonna go to a shop they can trust where they can watch their tires get filled with nitro and be SURE they get what they paid for!!!


Unless one has a nail in the tire or something, because the public can usually understand why a tire went low if there's a nail in it.










The whole 'Nitrogen in your tires' scam being pushed on the general public is simply fleecing the people that don't understand basic Laws of Physics. And NASCAR fans.

Honda does not approve its use, they issued a service news article titled, "Filling Tires With Nitrogen: Why We Say No". I don't know of any other auto manufacturers that do approve of its use.
The good I see here is that it isn't actually harmful, you don't lose anything but some money.

One application I read about where it actually made real damn good sense to use it in the tires was ........on the space shuttles.


/sermon

sdaidoji

iTrader: (1)

yeah, there are some wheels that have two valves, on opposite sides of the diameter. they claim this is easier to purge the air while filling with N2. of course, it will still retain certain % of non-N2, but should be slightly better than mounting a tire full of normal air and then trying to add only N2...

mac25

hahaah, lol. ya N2 is probably a scam.

we should just fill our tires with NOS =D, NO2. That must be the best of both worlds, lol.

ezone

Man, if I had been the one to get the public to pay for it I'd have my own private island by now.

Technically it's N2O, not NO2.

N2O is Nitrous Oxide
NO2 is Nitrogen Dioxide
NO is Nitric Oxide or Nitrogen Oxide


/geek

h4ldol

I finally got the Schrader retrofit TMPS kit installed in my new wheels and it's great. I switched out the rubber valve stems with some Schrader aluminum stems which improves the look better (and the longevity/reliability of the seal too I'm sure since the aluminum stem actually has a nut whereas the rubber one does not). It works great, the receiver sits nicely on the front of the dash above the stereo, and these are internal so there are no eyesore sensors sitting on the end of the valve stems.

I highly recommend them! (although they are really hard to find anywhere online right now, probably due to the CA port strike).

ezone

Give it a few years, those damn things will corrode and leak or be stuck in place. My first one to leak on my 18" wheels only took 2 years. I have now coated the threads and seal with dielectric silicone paste in an attempt to help it last.



OE's have been moving away from those and going to this style with the much more reliable rubber stem:

h4ldol

Lol, I replaced the rubber ones with the aluminum ones! Oh well, I have the rubber ones in case I ever want to replace it in the future I guess. I didn't think the seal would be as good since it doesn't have a nut to keep the valve stem secured in the hole as well but I'll have to wait and see how they hold up I guess. I hope they last at least a good 5 years.

5johny5

I think the whole N2 thing is crap, but i think it has to due with moisture in the air instead of the oxygen. Steam expands at a much bigger rate than just plain air and that can give you a big difference in your tire pressure. That is why NASCAR uses N2 is for its consistency in pressure growth instead of leak resistance.