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Old 04-14-2016, 11:59 AM   #21
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Originally Posted by Tireman9 View Post
Contained Air Temperature (CAT) and temperature of a sensor wipping around in outside are can be 20F to 30F or possibly more different. The TPM can only read the temperature it is exposed to.
Air is a good insulator and I doubt there is much air turbulence or movement of the air in the valve stem.
Now a metal stem might conduct some heat from CAT to outer end but it would also cool the stem too.
As I said I have measured and observed the significant difference between CAT and external readings.
Tire PRESSURE Monitor Systems are primarily for measuring and reporting and warning of PRESSURE changes.
Tire Temperature is a secondary issue and people spend too much time on that topic.
Yep. I did have metal stems installed when the new tires were mounted, but they all have this sealing grommet between the stem and the rim, so I'm not sure how much difference they actually make as far as temp data. I read your blog about the IR temp guns. I have a high quality Klein IR gun and I use it to "shoot" the tires and the rims/hubs, in case a bearing began running warm.

Your blog post was very informative about where the tire temps are actually hottest. I always assumed it would be the sidewall due to flex, but that's not where most of the flex is happening. So thanks for that information...made perfect sense.

I get that the IR guns are just marginally informative, but wouldn't it still be better than the TST system? Even though it's not giving precise data, it should still tell me if one tire is running hotter than the other three...although, the pressures would probably be the first data point to point out the hot tire, especially if it exceeds the setpoint.

Thanks Tireman;
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Old 04-14-2016, 12:03 PM   #22
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You are overthinking it. Set the tires in the morning and leave it alone.
I respectfully disagree Dan. My past experiences suggest strongly that not thinking about it is what gets us in trouble. Education and a better understanding of how all these systems work, place us in a much better position to either prevent a failure, or being able to repair a failure.

I would much prefer to prevent if possible, since working on trucks and campers on the side of an interstate in 95 degree weather with 95% humidity is not my idea of a fun day.

my 2 pennies

dg
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Old 04-14-2016, 12:40 PM   #23
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I respectfully disagree Dan. My past experiences suggest strongly that not thinking about it is what gets us in trouble. Education and a better understanding of how all these systems work, place us in a much better position to either prevent a failure, or being able to repair a failure.

I would much prefer to prevent if possible, since working on trucks and campers on the side of an interstate in 95 degree weather with 95% humidity is not my idea of a fun day.

my 2 pennies

dg
Of course you think about it. Even watch your tire pressure monitoring for pressure and temperature. But in my opinion chasing the tire pressure up and down each day is insane. :-)

Our local expert and your tire manufacturer has advised against letting air out of the tire in the morning to compensate for temperature rise during the day.
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Old 04-14-2016, 01:07 PM   #24
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You are overthinking it. Set the tires in the morning and leave it alone.

X2
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Old 04-14-2016, 01:15 PM   #25
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Yep. I did have metal stems installed when the new tires were mounted, but they all have this sealing grommet between the stem and the rim, so I'm not sure how much difference they actually make as far as temp data. I read your blog about the IR temp guns. I have a high quality Klein IR gun and I use it to "shoot" the tires and the rims/hubs, in case a bearing began running warm.

Your blog post was very informative about where the tire temps are actually hottest. I always assumed it would be the sidewall due to flex, but that's not where most of the flex is happening. So thanks for that information...made perfect sense.

I get that the IR guns are just marginally informative, but wouldn't it still be better than the TST system? Even though it's not giving precise data, it should still tell me if one tire is running hotter than the other three...although, the pressures would probably be the first data point to point out the hot tire, especially if it exceeds the setpoint.

Thanks Tireman;
Yes you can see temp differences but unless there is a serious problem I usually only see side to side dif when the Sun is on one side for long time.

If you have confirmed you are only loading tires to about 85% of their max and you run the tire sidewall pressure on your TT and have accurate hand gauge you will soon learn that TPM temp readings vary +/- 5 F (or more in the Sun or rain or snow) but the difference should be relatively constant.

On My Class-C my front sensors are right on the stems and the sensor is even shielded by the simulator hub caps. The dual rears have hoses 8" to about 15" long and sensors are out in the open. I see the difference between CAT and TPMS is much greater on the rears than on the fronts.

I suggest that people stop worrying about the temperature and just be sure you have set the TPMS warning levels (Low, rapid & Fast) so that you will never operate below the inflation needed to support the measured load on that tire.
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Old 04-14-2016, 01:43 PM   #26
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Of course you think about it. Even watch your tire pressure monitoring for pressure and temperature. But in my opinion chasing the tire pressure up and down each day is insane. :-)

Our local expert and your tire manufacturer has advised against letting air out of the tire in the morning to compensate for temperature rise during the day.
Dang Dan, don't believe I've ever mentioned chasing pressures up and down. Please don't put words in my post. I asked once about starting at a couple psi lower in anticipation of heat and pressures rising, but that one question was resolved back on page 1. No reason to be insulting. The rest of us are just having a great informative discourse.

G'day
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Old 04-14-2016, 01:48 PM   #27
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Yes you can see temp differences but unless there is a serious problem I usually only see side to side dif when the Sun is on one side for long time.

If you have confirmed you are only loading tires to about 85% of their max and you run the tire sidewall pressure on your TT and have accurate hand gauge you will soon learn that TPM temp readings vary +/- 5 F (or more in the Sun or rain or snow) but the difference should be relatively constant.

On My Class-C my front sensors are right on the stems and the sensor is even shielded by the simulator hub caps. The dual rears have hoses 8" to about 15" long and sensors are out in the open. I see the difference between CAT and TPMS is much greater on the rears than on the fronts.

I suggest that people stop worrying about the temperature and just be sure you have set the TPMS warning levels (Low, rapid & Fast) so that you will never operate below the inflation needed to support the measured load on that tire.
Tireman, based on a lot of information gleaned from this thread and others, I will just run the tires at max cold inf pressure. I plan to stop at a cat scale one day soon and at least get axle weight data. Would love to get individual tire weights, but that type of scale doesn't exist anywhere close.
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Old 04-14-2016, 03:07 PM   #28
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X2
Thank you sir. :-)
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Old 04-14-2016, 03:09 PM   #29
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David, not you but someone else on page 2 said they were still going to lower their pressure in the morning by 2 to 3 pounds even after listening to our tire expert recommendations not to do that.
It just seems that there's a lot of grief going on about nothing.

And I did have a :-) and that post also :-)

Relax and enjoy the ride!
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Old 04-14-2016, 03:11 PM   #30
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You are way over thinking this. I drive and own several 18 wheelers. They operate all over the US. In the south, southwest and west during the summer. I keep all my tire pressures at 110 lbs COLD. (flatbed trucks that are loaded heavy all the time) My steer tires at at 120 lbs. The only times I have to adjust the pressure is in the fall when the weather turns and stays cold, requiring air to be put in to maintain the 110 lbs. In the spring when the weather warms up and stays warm I have to let air out to maintain the 110. So, I keep my tires at this pressure all the time. No matter what part of the country I operate in I do not have problems with over inflation traveling through the desert or underinflation traveling through northern states or Canada. I treat my 5th wheel the same way. It calls for 80 lbs of air pressure COLD. Thats what I run, period. I have never had any issues in MANY years of doing this. My advice is to set your tires at the manufacturers COLD pressure rating and keep it there when starting out. I think your reading too much into it. TPMS can be a good thing, but they can cause us to be paranoid too I believe.
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