Temperature/Pressure differences

[murry135]

Don and Fellow members,

I have been watching my Valor TPMS and comparing the PSI vs TEMP readings. I see a 9-10 degree difference between tires that show the same PSI when running done the road. When at rest the TEMP differences reduce to 3-5 degrees. What may be happening and what is the +/- for PSI vs TEMPS and what is the +/- for TEMP readings? Are my readins within limits? The tires relecting the differences are not on the same side, they are different axels and different sides, diagnolly across from each other.
(ODS front and Doorside rear are the hight TEMP tires)

Murry

 

[Valor-Don]

Murray
During testing at Goodyear when the tires are in the identical environment and no differences or external factors then the temp is within 1 degree. When tires are parked, there are so many things affecting the resting temp, from shade and sun to wind and external heat sources. When traveling, there are so many things that could affect tire temperature
1. Tread depth
2. Differences in rubber durometer
3. Standard variances in manufacturing process of the tire
4. Standard variances in materials used
5. Differences in weight on the tire
6. Axel position and alignment
7. Many more
9 – 10 degree will not move the tire pressure more than 1 psi.
Normal specs for sensor are +- 1.5 psi +- 1.5 degrees F

Hope this answers your questions.

Don

 

[azbigfoot]

Hi Murry,

Wonder how much heat is being transferred from the hub/axle to the sensors which I believe are strapped to the inside of the rim. Maybe you have slight brake drag or differences in the functioning of the wheel bearings. Or are the tires tracking/aligned properly. Of course that doesn't make sense for when it is at rest (assuming cold temps and no sun on the tires). I would assume all the temperature sensors would read within a degree or two just before sunrise.

Next time I tow my Landmark I will check the temps which I don't monitor regularly.

 

[Garypowell]

I wondered the same thing when I first put on the Valor TPMS system. For one thing I have been involved in two major changes to the digital world in my career. And it was amazing what you would see once you compared the new to the old way. Many people drug there feet because "that can't be right syndrome"....but in fact they were seeing what was going on all the time and just now had a way to know it for sure.

So it is a good question but I see differences in each wheel....they never match up with infra red temperature reading and a manual gauge. But I have watched long enough now to know it is what it is.

And as Don points out above.....lots of variables.

 

[rxbristol]

I've seen the same thing with the right side reading a slightly higher temperature than the left. The right side is the lighter side. I was thinking it may because the truck's exhaust is porting directly in line to the tires---maybe?

 

[SeattleLion]

I've noticed similar differences. Over the summer I have watched the temps carefully. In our case, the right side is often 10 degrees warmer than the left. Just as I was about to go, "Ah Hah!" the left side was warmer. I think it has more to do with the road. On a high-crowned road, the trailer is leaning slightly to one side. I suspect this could cause more friction and hence, a higher temp.

One more little tire factoid: the "cold" inflation pressure varies depending on the temp of the tire. Endless people on here insist this isn't true, so i did some experimenting. While my trailer was parked, I took readings. On a 70 degree day, the pressure was 80psi all around (the pressure called for). Within a few hours, with the trailer never moving, I read the pressure when the tires and air was 55 degrees. Now it was 76 psi all around. At 80 degrees, it was 84 psi.

This, of course, makes sense. I read somewhere (sorry, forgot where) that the cold inflation rating was at 70 degrees F. One good thing about a TPMS, it is easy to see the pressure/temperature changes. Do I think it matters if you go to 80psi when it is 50 deg outside. Nope. Nor do I think it matters if I add air if on that same 50 deg day I see my pressure is now 76psi (it was 80 yesterday at 70 deg).

 

[murry135]

Thanks guy's for your input on this concern. Don I understand the variables that can affect the tire temps. You did answer my questions especially that 10 degrees can only account for +/- 1.5 lbs of PSI. I can see where air flow of hot exhaust from my TV can swirl under coach and cause variances in tire temps. As long as unit appears to be working within its standards I am happy. Thanks again to all contributors.