Accuracy of Temperatures Using TPMS

SilverRhino

Well-known member
Re: How did everybody come out on the scales?
Originally Posted by jnphobe
TST sets the minimum low pressure at 157* for their tempeture on the TPMS.

I wouldn't put too much stock into the temperature read out on valve mounted sensors. They are such a long way from the tyre that they don't represent rubber temperature very well at all.

Posted by:Willym

Copied this from another thread How did everybody come out on the scales? I copied this over to keep from stepping on the OP thread.

I have just installed a TST 507 TPMS on my truck and trailer and will be putting them to the test in a few days. Thought that when we are on the road that I would continue to stop and use my Infrared Thermometer to check tire temps and then compare to what the TPMS reads.

Has anyone done any type of actual comparisons to see how accurate the TPMS temps really are? The pressure reading I am receiving are right on.....Same as my tire gauge.

I was also very impressed with the 507 today.......Had the monitor in the house charging and it was reading the tire pressures on the truck parked out in the drive!

Travel Safe!
 

caissiel

Senior Member
It is acurate enough that when the cold pressure is lower in one tire that the tire air temperature while on the road will indicate much higher temperature on that sensor. I have a feeling that the area inside the rim where the sensor rotates is heated by the tire outside temperature and the sensor will sense it.

I also found out that the further the tire temperature is from 70F the more the tire pressure indicator is from the gauge pressure.

I have it figured that the sensor pressure calibrates the tire cold pressure to 70F. like at 34F it was at 110PSI on the gauge and 114PSI on the Monitor.

Now after adjusting the pressure to 110PSI at 70F on the gauge it shows exactly 110PSI on the monitor.
 

brianharrison

Well-known member
SilverRhino,

thanks for pulling this from the other thread and preventing the highjacking of the OPs question.

Regarding the accuracy of temps using external stem mounted TPMS - my opinion is it would be pretty inaccurate for actual temps, but it could give a trend to watch and to develop your own knowledge of a "comfort" range. A probe in the tire is the most accurate, measuring interanl air temp (inside the tire) with a rim mounted TPMS would be the next accurate, then a remote infrared gun would be less accurate and the least accurate would be a valve stem mounted TPMS. The reason I think the infrared gun would be less than an internal TPMS is because the tire may have temperature differences wherever it is currently measuring and it may not be repeatable every time - ie the tread edge would be different than the tread base, different than the sidewall, etc. In otherwords I am not sure about the repeatability.

The best tool to watch a tire is still the pressure monitoring - that's why they always say "a properly inflated tire.....".

The difference in hot vs cold running temperature is about 2 psi for every 10F above or below 70F (when set at 100 psi cold). I have a link to a site somewhere on my favorites and I'll link it to this post when I can find it.

Take care,
Brian
 

MC9

Well-known member
I have had a tst system for a couple of years. The Tire Rack link above is probably correct (for woosy little car tires) My truck tires hold about double the amount of air and more than double the pressure. As a result the temp and pressure numbers fluctuate at least twice as much.
 

cookie

Administrator
Staff member
Everybody is concerned about the accuracy of temperature monitors on the tires. As I see it the only value to knowing what the temperature is, is that they are all close to each other.
Not being a tire expert at what temp do I stop because they are too hot? I don't know.
My only concern is if seven tires are at 110* and one is at 180*, then I will have to look for a problem. I do know that there will be variances caused by sunshine on one side of the rig.
So for me the accuracy of the temperature is not as important as keeping an eye on uniformity.
JMHO.

Peace
Dave
 

rebootsemi

Well-known member
I agree with Dave here that all tires should be the same temp, got this off the Goodyear site:

The effects of temperature and atmospheric pressure.Air temperature and atmospheric pressure effect tire inflation pressure. If the outside temperature increases 10 o F,
tire inflation pressure increases approximately 2%. Conversely, when the outside temperature drops 10 o F, the tire
inflation pressure lowers approximately 2%.
Tire inflation pressure increases approximately .48 psi for every 1,000 feet of altitude due to changes in atmospheric
pressure. On the other hand, tire inflation pressure will decrease approximately .48 psi for every 1,000-foot decrease in altitude.
In other words, if there are changes in temperature or altitude during your trip, it’s important to check your tire
inflation more frequently.

Also a very good pdf from Goodyear on RV tires: http://www.goodyear.com/rv/pdf/rvbrochure.pdf
 

caissiel

Senior Member
Now here is an other twist in all those numbers. If you pump in air to increase your presure the air that will be pumped in will usualy be hotter, specialy if using a small tankless compressor that I use to pump up mine.

I just go with digital gauge pressure and I just pressed the sensor button and 110Psi on all 4 of mine. Suits me.
 

Willym

Well-known member
Everybody is concerned about the accuracy of temperature monitors on the tires. As I see it the only value to knowing what the temperature is, is that they are all close to each other.
Not being a tire expert at what temp do I stop because they are too hot? I don't know.
My only concern is if seven tires are at 110* and one is at 180*, then I will have to look for a problem. I do know that there will be variances caused by sunshine on one side of the rig.
So for me the accuracy of the temperature is not as important as keeping an eye on uniformity.
JMHO.

Peace
Dave
Sage advice as usual from Dave. For pressures and temperatures, uniformity is the key. Although you may find that the tyres on the sunny side run a little warmer and consequently have a slightly higher pressure. I prefer the IR gun to check tyre surface and hub temps. Differences may indicate a problem.
 

jnbhobe

Well-known member
Dave and I have talked about this many times and I agree with every thing he stated. The same goes for the pressure, none of the tires will read exactly the same, I just want to see them all at or above where I set them.
 
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