Hot Inside Duals

[Janet and Todd]

My inside duals heated to 145 degrees during the 1.5 hour drive from our summer place to home. Minimal braking was performed. What seemed weird was the silverleaf tire monitor went yellow for the inside duals and as they got warmer they would return to green and then back to yellow several minutes apart. I already have a dead battery in the right front monitor. I wonder if the readings are changing color because all the batteries are going. The outside air temp was 82 degrees and the tires smelled hot when I got home but no brake smell so I hope I'm not dragging a brake or something. Thoughts?

[RVPioneer]

What temps did you observe on the outside tires?
What psi readings did you observe?
What temps have you observed in the past under similar conditions?

Low pressure can lead to warmer temps. The inside tires can also pick up heat from the engine.

What TPMS sensors are you using?

[grindstone01]

I would be concerned, I try to keep my tires below the 130F temp. At 160F, tires reach a critical temp and the rubber will begin to degrade.

[Janet and Todd]

Originally Posted by RVPioneer

What temps did you observe on the outside tires?
What psi readings did you observe?
What temps have you observed in the past under similar conditions?

Low pressure can lead to warmer temps. The inside tires can also pick up heat from the engine.

What TPMS sensors are you using?

Outside tires were running around 120 F.
The 4 rear tires are 100 lbs cold. Fronts 110 lbs cold.

Outside duals were running around 117 F when the inside duals were heating past 130 F.

PSI's were nearing 130 psi on the front after an hour and a half on the freeway. The rears were cooler, around 120 psi.

Typically all the tires run cooler and I rarely get a yellow indicator on the Silverleaf but these are going from yellow then heating some more and going back to being in the green. Never saw that before.

The TPMS is "Smart Tire". Standard for the Apex.

[grindstone01]

I wonder if you had a hot brake/bearing issue that would only heat up the inside tires?

[bobkathy95]

Originally Posted by Janet and Todd

My inside duals heated to 145 degrees during the 1.5 hour drive from our summer place to home. Minimal braking was performed. What seemed weird was the silverleaf tire monitor went yellow for the inside duals and as they got warmer they would return to green and then back to yellow several minutes apart. I already have a dead battery in the right front monitor. I wonder if the readings are changing color because all the batteries are going. The outside air temp was 82 degrees and the tires smelled hot when I got home but no brake smell so I hope I'm not dragging a brake or something. Thoughts?

We run nearly the same PSI as you do (105 and 95) and have occasionally experienced similar unknown situations. Found no problem with wheels, tires, etc. Best guess - inside tires closer to heat of engine and exhaust ??? .
As for tire batteries, we have two that are failing/failed. Is it just a case of dismounting tires and replacing battery in sensing unit?

[whalepirot]

Originally Posted by bobkatgifts

Is it just a case of dismounting tires and replacing battery in sensing unit?

Not that I found. New units were required, with proper programming, as the batteries were not replaceable. YMMV.

[crockdar]

I noticed this once on our coach. I know you said you weren't using much brakes but how about engine brake? I saw this one time on our coach when driving through Tallahassee and using engine brake because of the traffic and all the traffic lights. I had never seen it before and have never seen it again. The high temps were on inside and the tags.

[Janet and Todd]

Just made an appointment with Bob Dickman Tire in Junction City for after Labor Day. I'm replacing all the sensors with new ones. Bendix bought the Smart Tire company for the tech and they are still making the "gold" series sending units (for the time being). The new "black" series don't work with Silverleaf so eventually this will be an obsolete system unless Silverleaf addresses it. The RF sensor won't wake up and the RR outside dual likes to sleep in for several miles before it wakes up and starts reporting.

I checked the tires cold this morning with my Longacres Racing tire gauge and all the tires are 6 pounds low so I will air them up properly and monitor the situation.

Oh, since all the sensors are being changed and we are due for new meats next year, I'll get the new Toyo's at the same time too. FMCA discount applies.

[RVPioneer]

That would be a great opportunity to weigh the coach to be sure you are running the correct pressures on properly rated tires.

[bobkathy95]

Originally Posted by Janet and Todd

Just made an appointment with Bob Dickman Tire in Junction City for after Labor Day. I'm replacing all the sensors with new ones. Bendix bought the Smart Tire company for the tech and they are still making the "gold" series sending units (for the time being). The new "black" series don't work with Silverleaf so eventually this will be an obsolete system unless Silverleaf addresses it. The RF sensor won't wake up and the RR outside dual likes to sleep in for several miles before it wakes up and starts reporting.

I checked the tires cold this morning with my Longacres Racing tire gauge and all the tires are 6 pounds low so I will air them up properly and monitor the situation.

Oh, since all the sensors are being changed and we are due for new meats next year, I'll get the new Toyo's at the same time too. FMCA discount applies.

Do you know the part numbers or costs of the sensors that will work with the Apex? I know I need my two front replaced. Thanks

[Alpine06]

Hi Janet and Todd,
I just went through a similar scenario.
Here a couple of tips:
Have the tire place take a picture of the sensor ID. This way if you would ever delete it from the Silverleaf you can simply add the ID back in.
Press the “Diag” button 4 times and you will see the table for the alarm settings “yellow” and “red” and also the voltage. If you think that the voltage caused the yellow you can simply lower it in this table. I add a pic of mine.

Next I would not take the 160F mentioned above to the bank. You might want to do your own research on that topic.
Both of my inside rear tires run always higher in temp in longer drives this is due to less cooling and the steel rim.
Also our Bendix sensor mounted inside the tire gives a better temp reading compared the the TPMS that is mounted to the valve stem. Something to keep in mind if someone reports tire temps.
Here a pic of the error table. I will change these values but this is how I received it with my coach. Note that I changed the error for the voltage to 0 for the first group just as a test.

[Tom and Patty]

Here is a response from Bridgestone back in 2005 regarding tire temperatures. Finally, the engineer doesn't say where the 200 degrees is measured, but it would seem if 90 degrees ambient plus 60, 150 would be about right. If your temps are higher than 60 degrees over ambient, then you might have a problem. You going to stop driving if it is 110 outside? You will be over 150 degrees.
This is just an opinion of one engineer and not my advice. Make your own decisions that you feel comfortable with. Also the key words are "properly inflated and loaded tire."




My question:
With air pressure and tire temp sensors installed in aluminum wheels, what kind of temperatures should be observed while driving in 90 to 100 degree temperatures?
What air temperature reading would be too high? I am using the Smart Tire system.


Answer:


Dear Tom,

Thank you for the opportunity to be of assistance.

The answer to your question depends on a number of factors, and quite frankly, there is not a hard and fast rule.

There are basically (3) types of tire temperature measurement
Probes inserted into the tire
Contained air temperature (which your system uses)
Tread (surface) temperature

A probe inserted into the tire – into either the belt edge or the bead area – the hottest points of the tire – is the most accurate method; however, it can only be performed under controlled conditions.

The contained air temperature method is the next most accurate, however, it is affected by the mounting system of the sensor – if the sensor is attached to the wheel, it will pick up heat from the wheel (which is picking up heat from the brake drum); and if it is attached to the tire interior, it will pick up heat from the casing.

Tread (surface) temperature is the least accurate, since measurement is normally performed by a hand held unit, thus hampering repeatability, plus the question of where do you measure? The ribs will be cooler than the grooves, and the center will be cooler than the shoulders, etc.

So, while all this has so far done little to answer your question, hopefully it has shed some light as to why I am being a bit reserved in my answer.

Now, what can I say to try to address your question?

While this is not set in stone: A very general rule of thumb is that a properly inflated/loaded tire, when up to operating temperature – one hour+ operation - will typically run about 60 degrees F. hotter than the ambient temperature. Anything above 200 degrees F. could lead to tire degradation and you need to investigate for a problem.


I hope this has answered your question to your satisfaction; if not, or if you have any other questions, please feel free to contact me.

[DrDaveMA]

Janet and Todd, do you have the original tire sizes on both the inner and outer rims? The reason I ask is if not there could be rubbing going on. I would expect if there was both tires would get heated, but maybe not equally? Look closely at the clearance and at the tire sizes. I believe in 2006 WRV was still using the 11R22.5’s some owners switched over to metric size tires and if your PO did so you could have some rubbing going on. Obviously the other factor is loading, get a good 4 corner weight and see where you stand. At all of the FMCA shows there is a vendor that does it, there might be people at other large RV shows or folks have used truck weight stations when they are not busy, depends upon the people doing the weighting and the state policy, it also means you have to put 1 tire position on the scale at a time, which sometimes can be an issue. I have heard some states leave the scales on when the station is closed, but I have never done that. You might also call your tire manufacturer and ask them if the temperature difference is normal.

Good luck sorting it out.