Tire Temperature

[wmtire]

OK, there is no need to get all upset over any of this.

I will state that many of the TPMS sensors (including GM) do indeed collect/transmit temperature readings. We use the Bartec 400 SD tool in our shop, and it does display the temp readings.

If ya will hold off a little, I have an uninstalled TOYOTA new TPMS sensor in the box (the vehicle is not here), and will take a pic of this display from the tool.

EDIT: This is taken from the Bartec site, which explains what information the sensors collect/monitor.

What is a Tire Pressure Sensor?

Direct tire sensors which transmit real time tire pressure information to the driver of the vehicle either via either a dashboard display or a warning light. The sensors are physical pressure and temperature transducers which are attached to the back of the valve stem or are in a form which is banded to the wheel.

The sensors are manufactured by international companies such as Schrader, Siemens, TRW, Pacific, Lear, Beru and others. There is no common technical standard for the sensors and the OE's and suppliers have generated a multitude of sensor designs.

The sensors transmit data such as their unique sensor ID, pressure, temperature and battery status (where applicable) and other diagnostic information. This data is sent to the Engine Control Unit (ECU) or specific receiver on the vehicle. Those vehicles which have graphical displays of the sensor positions can then identify which wheel position has a problem.

[wmtire]

Alright, here is the printout of the new TPMS sensor, that is not installed in a vehicle......thus the air pressure of 0 psi.

As you can see, it does indeed have the temp reading of 73 degrees....which is what it also says on our AC/Heat thermostat in the office.

[SKnight]

The tool I used is the Techsmart T55001, which is made by ATEQ for us, in case anyone was wondering.

[OldCoot]

Originally Posted by Airdale

Excerpt from the Michelin Tire Service Manual.

“Generally, As a radial tire revolves during operation, heat is generated on the inside of the tire at 4 degrees per minute. However, the tire loses heat at the rate of 3 degrees per minute with dissipation throughout the casing and air flow around the tire. After 40 minutes of continuous operation, the temperature has increased 40 degrees Fahrenheit. As the temperature inside the tire increases, the inflation pressure also increases. Thus, a tire inflated to 80 psi cold would now be 85 psi. because the inflation pressure has increased, the amount of tire flexing has decreased, which decreases the amount of heat generated per minute to 3 degrees per minute. Assuming the heat dissipation factor is still 3 degrees Fahrenheit per minute, the net temperature change is nil (0). This is called thermal equilibrium.”

Airdale

With my TST TPMS system I have never noticed a 40° temperature increase and normally tow 2-4 hrs without stopping. Max has been about 20° over ambient when towing with the ambient between 70° and 90°.

[acadianbob]

Originally Posted by OldCoot

With my TST TPMS system I have never noticed a 40° temperature increase and normally tow 2-4 hrs without stopping. Max has been about 20° over ambient when towing with the ambient between 70° and 90°.

This has been my experience too. I'm normally about 10 degrees over ambient but I have lots of excess load capacity. This on all-day towing trips.

[SKnight]

Tires do have a great cooling system, consider this, the top half of the tire, because it's effectively moving forward, has up to 130mph of wind cooling it off!

The bottom of the tire, being hopefully locked to the ground, is going up to 65mph, but if you look at at a tire rotating, while the top of the tire is also going 65mph, it's going 65 in the opposite direction. Because you're moving forward, there's 65mph of wind going by, and the top of the tire is going 65mph against it, thus the differential is 130mph!

[BamaBob]

Originally Posted by OldCoot

I got the popcorn concession for this one covered.

OK but I'm taking my cut with the beer sales

[OldCoot]

Originally Posted by SKnight

Tires do have a great cooling system, consider this, the top half of the tire, because it's effectively moving forward, has up to 130mph of wind cooling it off!

The bottom of the tire, being hopefully locked to the ground, is going up to 65mph, but if you look at at a tire rotating, while the top of the tire is also going 65mph, it's going 65 in the opposite direction. Because you're moving forward, there's 65mph of wind going by, and the top of the tire is going 65mph against it, thus the differential is 130mph!

Big problem with that is the tops of the tires are enclosed and not subject to the wind over the top.

[BamaBob]

X2 AcadianBob & OldCoot - we just took our rig on a all-interstate trip to South GA 2 weeks ago - ambient temps were in the mid 70s and i do not recall my TST TPMS 270 ever registering temps over 80 deg

Edit: I wonder how high temps would go if, for example, you were driving I-10 through AZ in July with ambient temps @110 deg?

[acadianbob]

Originally Posted by HSVBamaBob

Edit: I wonder how high temps would go if, for example, you were driving I-10 through AZ in July with ambient temps @110 deg?

I've wondered about that too. Even Wyoming in July can be darn hot.

[cadman99]

Her's what Michelin says ........

"A tire in operation will heat up until it reaches its equilibrium temperature where the heat being generated equals the heat being dissipated.
The temperature of the tire will increase with an increase in ambient temperature. There is nothing to worry about in the ranges stated (120-125°), if the temperature gets above 250 degrees F then I would be concerned !"

[OldCoot]

From page 2 of TST manual: "Truck System Technologies"
What should I set my parameters at?... As for temperature, the monitors are preset at 157° F, a safe setting for all tires, which typically fail between 180°-200° F.

[shineysideup]

Originally Posted by HSVBamaBob

X2 AcadianBob & OldCoot - we just took our rig on a all-interstate trip to South GA 2 weeks ago - ambient temps were in the mid 70s and i do not recall my TST TPMS 270 ever registering temps over 80 deg

Edit: I wonder how high temps would go if, for example, you were driving I-10 through AZ in July with ambient temps @110 deg?

We were in Gorman CA. last year on July 13. I know it was stinking hot (I found temps for the area last year were around 100 F. I just happened to take some pictures!

[cadman99]

The Michelin response was a bit puzzling to me - Anything over 200° would seem dangerous. None the less under-inflation, speed and ambient temperature are the biggest factors in tire temps.

[SKnight]

If your tires hit 250 and are still holding air I would be very surprised.

[OldCoot]

Originally Posted by SKnight

If your tires hit 250 and are still holding air I would be very surprised.

I would be surprised if they survived at 180D.

[Tireman9]

Some good info here plus some confusion about the reality of tire performance. In my test of 5/19/12 a temperature difference of 20F was noted between the TPMS which is on the end of a metal stem that is cooled by moving in ambient.
The hot spot is buried deep in the tire structure at the belt edges and this can only be measured accurately with a needle probe.
IR guns read tire surface temperature which can vary by 10 to 30F over a distance as small as 1/4" so a reading from an IR gun is more of an average temperature over a circular area that is sometimes 1" diameter.

TPMS are primarily a pressure sensor designed to give the driver a warning when a certain amount of pressure is lost. Some only warn when the pressure drops 15% below the cold pressure set point while others also warn with a certain number of psi loss from the hot pressure.

I agree with those that don't pay much attention to the temperature except when the alarm goes off. This is most likely a bearing or brake issue. My TPMS displays pressure & temp but I really only pay attention to the pressure and the temperature is just some extra numbers that go up and down over a relatively small range.

Finally the temperature that you are reading relative to ambient can be anywhere from 10 to 60 degrees above ambient with things such a tread depth, actual load, inflation, moisture content in the inflation gas, free air clearance around the tire, length and material of valve stem etc. all having an effect.

[BamaBob]

Originally Posted by shineysideup

We were in Gorman CA. last year on July 13. I know it was stinking hot (I found temps for the area last year were around 100 F. I just happened to take some pictures!

Wow 132º is pretty warm! I'm like others and would get concerned if it got 20-30º hotter!

[OldCoot]

[QUOTE=Tireman9;598100...I agree with those that don't pay much attention to the temperature except when the alarm goes off. This is most likely a bearing or brake issue. My TPMS displays pressure & temp but I really only pay attention to the pressure and the temperature is just some extra numbers that go up and down over a relatively small range...[/QUOTE]

When my temperature alarm went off it was sure not a bearing or brake issue as the trailer has now traveled over 9,800 miles since it went off. The alarm was set too close to ambient due to me being overly cautious. I have since set it 5 degrees higher and have towed in much higher ambient temps without it going off. I think anyone who ignores the temperature alarm however inaccurate you claim they are will be courting a blowout, tire disintegration, burnt bearing or brakes. Whatever the cause of the temperature rise, I would rather have it than not and will continue to monitor. I really doubt if the temperature will read on the monitor in time to keep the bearing from disintegrating before it is detected.

[Tireman9]

Originally Posted by OldCoot

When my temperature alarm went off it was sure not a bearing or brake issue as the trailer has now traveled over 9,800 miles since it went off. The alarm was set too close to ambient due to me being overly cautious. I have since set it 5 degrees higher and have towed in much higher ambient temps without it going off. I think anyone who ignores the temperature alarm however inaccurate you claim they are will be courting a blowout, tire disintegration, burnt bearing or brakes. Whatever the cause of the temperature rise, I would rather have it than not and will continue to monitor. I really doubt if the temperature will read on the monitor in time to keep the bearing from disintegrating before it is detected.

I'm a bit confused. You say your only experience from a High Temp warning was due to your setting the level too low. How is this a statement that supports using the temp warning as an early warning of a tire failure?

"Blowouts" and the sidewall disintegration are a direct result of excess heat generation internal to the tire sidewall body cord due to extreme flexing that comes from air leaking out of the tire and having lost 20% to 60% of your air.
In my experience as a tire engineer, the low pressure warning will always precede a high temperature warning if we are talking about sidewall flex failure.

If you want to be conservative on any setting it should be the low pressure setting. You should be able to set the warning at cold pressure -10% rather than -15% by simply setting the TPMS "Set Pressure" 5% higher than your goal. An alternative is to ensure the Fast leak and Rapid leak warning levels, that warn of pressure loss from the Hot running pressure, are also set properly.

We do agree that the Temp warning is probably useless for warning of bearing failure but I think a stuck and dragging brake might raise the contained air temperature to give a warning that something was wrong and a potential of giving some warning is better than no warning at all.