Tire pressure/temperature rise

[Bourbon County]

We just returned yesterday from a camping trip and saw some puzzling readings on the TPMS. I only have readings on 3 tires since the spare was on the L/H front. It was put in service due to a flat along the way and I didn't take time to put the sensor on.

The R/H rear is where I saw the puzzling readings. The other 2 tires had built up to 85 and 81 PSI, and 84 and 85 degrees F. The R/H rear built up to 88 PSI and 95 degrees. It was a very mild day and outdoor temperatures were in mid 60s, I very rarely drive over 65-70 mph.

I'm very conscious (actually totally anal) about tire care and had all 4 inflated to exactly 80PSI before I left. I checked on a 75 degree day with a very good pressure gauge. Even though it's a cheap model, my TPMS reads very accurately in comparison to the gauge. I run Goodyear Endurance tires.

Am I possibly seeing warning signs that a wheel bearing is going out? I actually own a small thermal camera and should have taken some images, but it was raining when we got home and rushed around to get unpacked and failed to do so.

[MandK]

Hard to say. The IR gun readings on the drum/hub would help you try to get a handle on it. It also could be a shoe dragging, but that 1 tire is high.
Actually, I would expect to see higher readings on the other tires although you didn't mention how long of a trip it was. I routinely see 10-15 psi and 10-15 degrees difference when pulling in those temperatures at 65 mph, but I have 110psi tires and a little heavier I am guessing, trailer.
I would look at the brakes first. My drum brakes worked as best they could before I converted to discs and the tire temperatures and IR readings on the hubs all run much more consistent now with the discs. I think sometimes the electric brakes don't work evenly, causing one wheel to do more braking. Other opinions will follow. Good luck.

[Lee-CI]

I agree with Mark on possible brake drag on the RR. The only other thing that comes to mind is if one is towing the fiver nose high. If so then that would cause more weight to be shifted to the rear axle. I would jack the tire up off the ground and spin it by hand to check for excessive drag.

[Rotnjonny]

I have seen dramatic temperature differences from side to side on cold tires that have been sitting over night. What I found was that the sun on one side of the 5’er will significant change tire temperature on cold tires. I don’t necessary think that applies to your situation, other than to say that temperatures can be impacted by a multitude of conditions.

[jadatis]

Forget the temperature readings of tmps.
You most likely have external sensors, that give pretty exact the temperature at the end of the valve, and not of tire-inside gascompound.

But it can be calculated back from the pressure - rising. Roughly for 80 psi filled at 70 degrF, the temp changes 5.5 degrF per 1 psi change.
But if you use it for 60 degrF filled, it wont give dramatic differences.

So tire inside rises to, if 88psi measured, to 8x 5.5 degr F is 44 degr Hotter then cold filled is 114 degrF. if filled at 70 degrF 80 psi.


Recently made a tirepressure /temperature calculator spreadsheet, both ways, temp for pressure, and pressure for temperature.
And, and in that I am first, for if dry gascompound, and if enaugh water in tire, call it wet.
If you want to play with it, mail me at my hotmail. com adress with usernane jadatis, and I send it in return.
Combine my mailadress yourselfes, spamm-machines cant this way.

What do you mean with R/H, right hand or something?
But thst one tire higher temp inside, might be because of hanging brake or something.

[BB_TX]

My sunny side tire temps always run warmer than the shady side tires no matter what the ambient air temp was.

Actually my shady side tires ran only slightly above ambient even at 70 mph.

[432bartman]

Originally Posted by BB_TX

My sunny side tire temps always run warmer than the shady side tires no matter what the ambient air temp was.

Actually my shady side tires ran only slightly above ambient even at 70 mph.

Same with mine

[rohrmann]

Those pressures and temperatures are negligible increases, nothing to worry about. Not only does the direction of the sun play into the temperatures but the road surface too. Even the crown of the road can put additional load on the right side of the trailer. Also, you might consider upgrading to heavier tires. For a rig that has a GVWR of 16,625 lbs, you are probably maxing out the 7,000 axles and you don't have much or any available safety margin on the Endurance tires. The 235/85R16 only has max capacity of 3640 lbs, so no where near a 10% cushion that is recommended lately. If you are running the 80 series tire, it is only 3420 lbs. A heavier tire will also run cooler because it won't flex as much as the E range tires. You might consider the Sailun S637 G range tires. Those are standard equipment on all Montana's now.

[Bourbon County]

Thanks to all that have responded so far, I'll try to answer some of your questions.

The trip was about 225 miles, it was either raining or almost totally overcast the entire trip, I don't think solar gain was an issue. If anything the pavement was probably cooler too. I have a Flir thermal camera, not just an IR gun, it would have been a very good use to take images while they were still hot. I have the Flir Tools software too and you can pick out hot spot(s) very easily. I'm also a level III thermographer and was part of my job prior to retiring.

I'm not so concerned about the actual temp/pressure readings as much as the delta. The tire on same side directly in front of the problem child was 10 degrees cooler and 7 PSI lower. Identical tire, same age/mileage. I realize that the temperature on the TPMS may not be highly accurate. Even the rule of thumb of a 1 PSI rise per 10 degree temp rise doesn't work out in this case.

I have considered Sailun's but have a big hurdle to overcome. In 1968 my older brother got a government funded trip to Vietnam and returned less than 90 days later in a body bag that was guarded by soldiers and never allowed to be opened even for the wake. I have no prejudice against the Vietnamese people, but try very hard to prevent sending any of my hard earned $ to that country.

I do believe the brake on that wheel deserves a good look. If I ever get my mowing caught up I might just hook up and take it for a ride down the interstate and come back and shoot it with the Flir before I tear into it. I'll try to post those thermal images

[mlh]

Tires are designed for a pressure increase while running. There is nothing to worry about. The pressure increase depends on speed, air temperature, road temperature, pressure and other conditions.
Lynwood

[Montana Man]

Accuracy of the sensors are about +- 3%. I would change positions of sensors and see what happens.

[twindman]

Is your rig nose high when towing? If so that throws a little extra weight on the rear axle. And I think on my rig, the side with the fridge and water heater is heavier, so I think that makes the tires run higher pressure.

[jadatis]

Did not think of that higher nose, but could certainly be an explanation.
Then on other side of that axle the spare, wich had no sensor, but most likely same pressure, or only a bit different, because of weightdifference R/L.

Then that could also explain the blowing tire, and you have to salve it by finding a way to get the nose lower. Or if not possible put some filling at the suspension of front axle. Temporary solution is put the frontaxle higher pressure, wich gives lesser deflection, so a bit better weightdivision between the axles.

Edit: read back spare on front axle.
But weightdifference can be crossed vetween the axles, has to do with dinamic balance instead of static balance, as is with a single axle trailer.

[Bourbon County]

Originally Posted by twindman

Is your rig nose high when towing? If so that throws a little extra weight on the rear axle. And I think on my rig, the side with the fridge and water heater is heavier, so I think that makes the tires run higher pressure.

You bring a good point. I've actually always thought it was a bit low. I will definitely hook up and try to find a level place to park and check it with my laser level. On my rig, there are 2 slides on the R/H side; one is the dining area, the other is the entertainment center and fireplace. The kitchen, water heater, and furnace are all on the L/H side. I know that weight distribution and balance are major factors for the designers, but from just a cursory look it would seem the L/H side would be heavier.

[Bourbon County]

Originally Posted by jadatis

Did not think of that higher nose, but could certainly be an explanation.
Then on other side of that axle the spare, wich had no sensor, but most likely same pressure, or only a bit different, because of weightdifference R/L.

Then that could also explain the blowing tire, and you have to salve it by finding a way to get the nose lower. Or if not possible put some filling at the suspension of front axle. Temporary solution is put the frontaxle higher pressure, wich gives lesser deflection, so a bit better weightdivision between the axles.

Edit: read back spare on front axle.
But weightdifference can be crossed vetween the axles, has to do with dinamic balance instead of static balance, as is with a single axle trailer.

Thanks for your response, I will be checking the towing level soon. Actually the lone sensor on the left side was on the same axle as the problem child. It was at 84 degrees and 85 PSI, not much more pressure but 10 degrees hotter.

[duane909]

Originally Posted by Bourbon County

I might just hook up and take it for a ride down the interstate and come back and shoot it with the Flir before I tear into it. I'll try to post those thermal images

If I could ask, what camera/flir do you have?
~Duane

[Bourbon County]

I have the C2 which I don't think they sell anymore. They do have a couple of models that will plug into an android or iphone. The Flir Tools is a free download software that's very much like the pro series.

I think I'm going to start carrying mine on camping trips in the future. I've never done it, but I know guys that use one to tell when their steaks are don.

[MARK A]

I've had sunshine make 10 psi difference.

[Todd727]

Did you weigh the axles individually? More weight on rear axle could cause this even if trailer isn't nose high.

[Bourbon County]

Originally Posted by Todd727

Did you weigh the axles individually? More weight on rear axle could cause this even if trailer isn't nose high.

No, I haven't; there is a truck stop with a set of CAT scales about 20 minutes away and I am certainly going to do that soon.