Tire Pressure Monitoring System (not the usual question)

[tmmar]

I have a TST tire pressure monitoring system that monitors the tire pressure and temperature. When I am travelling at highway speeds (between 65 and 70mph-where allowed of course) for several hours at a time, I frequently look at my monitor panel and take note of th e tire pressure and temperature. My tire temperatures never vary more than a few degrees from the outside ambient temperatures. If the air temperature is 75 degrees outside, my tire temperatures may read anywhere from 67-77 degrees. They never get any hotter.
For those of you that have a TPMS with pressure and temperature, what temperature readings do you normally see when travelling at highway speeds for a number of hours?
Thanks.

[dennisewitte]

Yep. I have eight sensors, four on the TV and four on the fifth wheel. They consistently read just a few degrees above the ambient, sometimes more if in slow moving traffic and the road surface is hot.

[Blackhat6mike]

It depends if it is on the sunny side or shadow side, the temps can vary MANY DEGREES. Don't let it scare you if your sunnyside temps are 30-40 degrees hotter as the sun has a lot of effect on your tires. I've seen 105 on one side and at the same time 77 on the other. It's the pressure you need to be most concerned with. Make sure they don't rise more than 30% of the cold max pressure or less than 10% below. If you get a slow leak, it will tell you.

[tmmar]

Sunny side or shadow side, the tire temps are always about the same as the outside ambient temperature. That is why I am wondering if my system is working correctly. I would think that the tire temperatures would rise the longer you are travelling at highway speeds and the outside temperature rises also.

[dan-nickie]

Mine was about the same. I got to where I don't really look at the temperature in anymore.

[Blackhat6mike]

I can't speak personally about coaches as I never had a TPMS on mine, but I can speak on TTs and the temps vary a lot.
On a coach, your inside tires never see the sun, so I would GUESS their temps would be consistent.

[Retired JSO]

Traveling week after Christmas in Florida, ambient temp 65 and tires were all around 90 degrees F.

[rick42wood]

I have 6 sensors on my TV, the temperatures run just above ambient on both sides. This is what tires should do with proper inflation while travelling. they are designed to be cooled by the air as the rotate. try checking the temperatures after the vehicle has been parked one side to the sun for a long time. You should be able to see a difference then.

[Oscarvan]

OK, first I want to know HOW the tire temp can be below ambient

Are they cooled?

So obviously the number presented is not realistic.

I do not (yet) have a TPMS on my coach but it is on the list.

I did have one on my fiver and monitored 12 tires. I can tell you that the sunny side is hotter, and so is the heavier side, even the heavier corner. (It was a tri-axle) The right rear tire (the one under the tail end of the galley) was the heavy one and always ran warmer.

Generally they ran 10ºF warmer than ambient, sunny/heavy ones 15-20. MoHo tires seem to run cooler as far as I can tell with my IR thermometer that I have been using on walkarounds during breaks. 5-7º above ambient, the sunny saide warmer, again.

So as none of these systems are calibrated to any standard and as MoHos and trailers appear to run differently I think the absolute number is immaterial.

Keep an eye on things and whatever the numbers are, those are the numbers. Now when ONE starts running above that by a significant amount THEN the time has come to get excited.

[Comanchecreek]

I run an EZGO TPMS on my truck and 5th Wheel. Temp is usually a function of the sun. If cloudy or dark tires usually read the same temp. Pressure will rise as temperature rises so keeping track of temp will keep you from panicking when pressure vary from side to side. Just an extra note; I run the flow through sensors which add 1.5 inches to the valve stem. Had rubber high pressure stems on. They will vibrate enough to cause the stem to crack. Am in the process of replacing all stems with metal high pressure stems. Found out the hard way, but got to my location without a flat. I know the alarm works.

[johng4706]

Originally Posted by Blackhat6mike

It depends if it is on the sunny side or shadow side, the temps can vary MANY DEGREES. Don't let it scare you if your sunnyside temps are 30-40 degrees hotter as the sun has a lot of effect on your tires. I've seen 105 on one side and at the same time 77 on the other. It's the pressure you need to be most concerned with. Make sure they don't rise more than 30% of the cold max pressure or less than 10% below. If you get a slow leak, it will tell you.

I too have the TST TPMS and have noticed similar results. Tires warm up once I get moving and both tires on the sunny side are a couple degrees warmer. (30 to 40 degrees sounds very high.) Same with TP. I might start at 48 psi, even as low as 45 psi depending on overnight temperatures. Once I get moving pressures build up to slightly over 50 to 55 psi. Target TP is 50 psi.

[conceptumator]

I have to side with the folks who say they have some pretty wide variance. This is our second Class A and we've had TPMS systems on both and the readings are pretty consistent between them, so I can't say it was a specific tire or vehicle. On our current coach, I have six monitors on the coach and four more on the toad. As others stated, depending on sunny side or shady side will matter, also if there's a bit of a slope to the roadyway it can cause a little bit of added heat buildup on one side of the coach. I've driven Texas and Florida in the summer quite a bit and ambient temps last July in Texas were about 108F with tire temps around 125F. Funny thing on the toad is that the right front tire, which is closest to the coach exhaust (it's a pusher) always runs almost exactly 10 degrees warmer than the other three tires on the toad. I think it really comes down to whatever you're used to seeing being normal and looking for variances from the norm. As someone else said, pressure is the important thing. The temp is on there to indicate possible other issues, like bad bearings, rubbing brakes, etc.

[tmmar]

Originally Posted by Oscarvan

OK, first I want to know HOW the tire temp can be below ambient

This can happen if the sensor is not functioning correctly. That is the main point of my post is whether or not the system I have is functioning the way it was designed to. Seems that from some of the replies, it is.

Thanks for all the replies.

[Burnking]

I have a TPMS but I am not sure what ranges to set on the system. If the tire pressure is 50 psi, what range should be set for hi/lo psi, also hi temp?

[Mr. Dan]

Originally Posted by Burnking

I have a TPMS but I am not sure what ranges to set on the system. If the tire pressure is 50 psi, what range should be set for hi/lo psi, also hi temp?

I think you have to experiment. I set my high pressure 7-8 lbs. over my desirable pressure and the system alarmed in 25-30 minutes. I jacked it up 2 lbs. and it alarmed before I got to my campground.

[hikerjohn7]

I use a Tire Minder tire pressure monitor and when I am on the highway, I consistently get temp readings as much as ten degrees above ambient. Readings in the high 90's and even over a hundred are common in summer in Florida when ambient is around 90.And the tires on the sunny side can show the highest temps.

[Delco Bobby]

Originally Posted by Blackhat6mike

It depends if it is on the sunny side or shadow side, the temps can vary MANY DEGREES. Don't let it scare you if your sunnyside temps are 30-40 degrees hotter as the sun has a lot of effect on your tires. I've seen 105 on one side and at the same time 77 on the other. It's the pressure you need to be most concerned with. Make sure they don't rise more than 30% of the cold max pressure or less than 10% below. If you get a slow leak, it will tell you.

My last trip on the Jersey Turnpike had me concerned for awhile. As the was a 15 to 20 degree difference between the sides. The sunny side was hotter. Generally I don't notice much of a difference.

On trip back at night both sides were about the same.

[Witch Doctor]

Originally Posted by Burnking

I have a TPMS but I am not sure what ranges to set on the system. If the tire pressure is 50 psi, what range should be set for hi/lo psi, also hi temp?

It should be or what they recommend is 10% under and 30% over I think. Leave the factory setting alone for high heat and pressure, I think it comes at 158 for high temp....If you want to know for sure, a call to TST will be in order, do you have the manual that came with them? I think it is also in there, but calling is easier, the receptionist can answer that for you, hell she programed (coded ) my sensors over the phone...

[FFred]

My butt gets sore with a lack of circulation , so every few hours we stop for a walk around.

A quick visual check and a few seconds with a lazer thermometer gun on all tires assures no underinflation.
\
No installation , no guessing , no maint. many other uses , for well under $50.

KISS

[johnbryanpeters]

Originally Posted by FFred

My butt gets sore with a lack of circulation , so every few hours we stop for a walk around.

A quick visual check and a few seconds with a lazer thermometer gun on all tires assures no underinflation.
\
No installation , no guessing , no maint. many other uses , for well under $50.

KISS

That does you exactly no good in the event of a significant puncture.

I recently purchased an EEZTire system and have been experimenting with it. Some comments:

• The temperature measurement is effectively ambient air temperature plus whatever might be radiated by the wheel. It's ineffective at measuring the temperature of the tire.
• The "theft prevention" on the non-flow through sensors is ludicrous. It's at best a dust cover, and if one tries to use the wrench to install the sensors, a lot of air is lost in the process.
• My sensors read at least 2 PGIG lower than my digital tire gauge. I'm still puzzling over which to believe.

Bottom line is that it's better than no TPMS, but wants to be taken with a grain of salt.