Tire Temperatures?

[cvd]

Short question – what range of tire temperatures are you seeing and what is the max before you should stop and let them cool?

Long version – I’ve been using a 10 position TPMS for many years (EEZ on prior coach, TST on new Europa). Am comfortable with monitoring the PSI swings as the tires heat up while driving, outside temps change, altitude changes etc. But, I’ve never paid attention to the tire temperatures.

On recent 2 week, 1,900 mile loop from CA to CO and back, on the last night, as I pulled into the parking spot, the TPMS started beeping with 160 degrees on the rear, inside passenger side tire. I didn’t note the other tire temps (should have). This leg of the trip was winding through northern AZ mountains, about 7,000 ft elevation.

The next day, on the 20 - 25 miles still in the mountains, that same tire went from 75 PSI/75 degrees cold to 90 PSI/125 degrees. PSI increase is normal, not sure about the temp. The other inside rear tire got up to 110 degrees. Once out of the mountains and for the rest of the way to Phoenix and across the desert to CA (100+ outside temps), all 4 rear tires stayed at approx. 100 – 105 degrees.

Quick research came up with:
1) Inside tires will be a couple degrees hotter due to less air flow, more sunshine, and because steel wheels displace heat less effectively than aluminum. But I had problems only on the passenger side inside tire and my swings were more than a couple degrees.

2) High altitude can make a small increase in tire pressure and heat. But I was in higher altitude several times when in CO than in AZ.

3) Excessive braking can heat up the brakes and tires. I’m very conscious of brake use when descending. BTW – I was very pleased with the single level ISB exhaust brake and the transmission. Came down west slope Wolf Creek Pass well controlled in 3’d gear

4) While I limited the use of the brake drums, the exhaust brake was used regularly. Don’t know if that increases exhaust heat and indirectly the tire heat (the exhaust pipe swings just in front of those rear passenger tires and exits close to the outside tire).

5) Guessing here – does a DEF regen cause an exhaust heat increase that would have noticeably heated up that inside tire?

6) The TPMS measures the temp at the sensor, just inside the valve stem. Thus, the tread temp will be higher than the TPMS reading. Next time out, I will use an infrared temp gun on the tire rubber and compare that to the TPMS temp reading (anyone done that?)

7) Internet wisdom seems to say tire temps up to 195 – 200 degrees are ok. But, that is for tread temp (I think). So, 160 degree TPMS reading is about the max you should allow the tires to reach (again, guessing).

Anyone researched this subject further?
Thx, Cliff

[NMWildcat]

Before TPMS, did any of us worry about tire temps? I know I never did and still don't, and I sometimes travel with ambient temps of 115.

All I monitor is if one tire/hub is SIGNIFICANTLY different from the others. And I only do that at fuel stops.

I refuse to constantly monitor everything, especially tire temps Some of my friends do this and they drive themselves nuts at times over nothing.

[vlamgat]

Originally Posted by NMWildcat

Before TPMS, did any of us worry about tire temps? I know I never did and still don't, and I sometimes travel with ambient temps of 115.

All I monitor is if one tire/hub is SIGNIFICANTLY different from the others. And I only do that at fuel stops.

I refuse to constantly monitor everything, especially tire temps Some of my friends do this and they drive themselves nuts at times over nothing.

I tend to agree with you. Analysis paralysis. But the OP was just asking the question and given our general lack of training in this arena, seeking a collective wisdom since none of us KNOW the answer.

With that said, I think he was on the right track in his perspective conclusions. Passenger side will run hotter because of exhaust proximity; and the inside will always be hotter than outside wheels for the reasons he surmised and possibly some others like differential heat transfer and wheel bearing proximity. But is 10 degrees excessive? Is it a trend forecasting a problem? After all thats why we track data at all. My view is not yet because as he points out once he got out of the mountains, the levels left/right were essentially the same. Once cannot account for all the variables that come into play going up and down those hills and I suspect that exacerbated the factors that raised one side above the other.

In addition, my experience has been that although one side may increase more than the other on any tire, they tend to stabilize as the OP posted. I would be concerned if that indicated 200F kept increasing but 200F is not excessive based on my experience.

Last point: Check the left/righ rear wheel weights at a CAT scale. Its possible that the passenger side is loaded more heavily than the driver's and in mountains this is reflected in the pressures and temperature.

[Peabs]

My thoughts with the caveat that they are not scientific, yet with a fair amount of research:
1. Initial low tire pressure creates more heat development. 75 psi seems too low for the Europa. While the Michelin load vs tire pressure chart may allow a pressure that low to carry the load. That low of a pressure may create more issues.
2. The TST TPMS is set to alarm at 158 degrees. But, it is adjustable and we should not be too worried about 160 degrees

3. The passenger side inner dual always runs hotter than the opposite side on our DX3-34KD. Probably due to exhaust proximity.
4. Due to the higher heat potential. Les Schwab replaced all of the plastic valve stem caps to stainless steel on our rig.
5. I still "thump" my rear tires even with the TPMS.
6. As stated, "analysis paralysis" can cause more worry that needed.
Enjoy the trip.

[NXR]

Unless the tire is underinflated or overloaded the temperature is irrelevant and just "feature creep". That's why the usual TPMS default is close to 160 F.

On a trailer having one hot tire can be indicative of a pending bearing failure or a dragging brake. On a motorhome? Not so much due to the much larger wheels and tires acting as a heat sink and radiating heat away.

The best use for a TPMS is as a trend monitor. If all tires are behaving more or less as they have in the past AND all tires are essentially behaving the same with respect to pressure and temperature you're golden.

It's when one tire starts acting weird that you need to investigate further.

Ray

[png31]

X2 on everything said here, and I’ll add do not underestimate the level of exhaust heat energy produced by these modern diesels, especially during a regen cycle. When the SCR equipped trucks started hitting the market, there were instances of utility bed type rigs experiencing spontaneous fires in the cargo compartments adjacent to the exhaust outlets, even those with diffuser tips. It was quickly learned to make certain the exhaust system was routed properly, and not to load flammable or temperature sensitive items in those compartments.

[jadatis]

Tire temperature must be split in parts.

1. Temperature of tire material, wich is higher in the middele of thick parts closer to tire inside gascompound , then on the outside, where it can be measured with a temperature gun or something.

2. Tire inside air or whatever gascompound.

That second is what makes the pressure rise.

I read from a man from tiremaker Nokian that tire-material max allowed temperature is 120 degrC/ 250 degr F.
Above that , rubbber hardens and by the bending of it when driving, little cracks are created.

Those tear further in time, again by the bending by driving, whatever you do after that.
Higher pressure then can even speed up the proces, and when tire then blows after 2 years, when damage builded up enaugh, the high pressure is blamed.
While in fact the tire was already lost that once overheating , by using to low pressure for the load on it., and speed used.


When descending the mountains the temperature in tire ( 2.) can rise to boiling point of water 100 degr C/ 212 degr F. by using the brakes to often. Then heat of brakes is transported trough the rims to tire inside air.

But then most likely the tire-material still not overheats, because speed is lower ( about 30 mph) and lesser deflection by the higher pressure, the higher temperature gives.

So then lesser cycles a second and lesser heatproduction a cycle, gives lesser heatproduction a second.

So though temperature in tire ( 2.) is related to the temperature of tire-material, external factors can make, that it goes out of line, and still no damage to tire-material.

I made a list for temperature and pressure, wich you can use to get an idea of what is normal and not.

In that I used 45 degr C/ 113 degr F , I estimated the tire inside gascompound gets , when driving with yust enaugh pressure for load and speed , in ambiënt temperature of freesing point 0 degr C/ 32 degr F. Then tire-material yust not overheated.

60 degr C/ 140 degr F , same story for driving in ambiënt temperature of 20 degrC/ 68 degrF.

75 degr C/ 167 degr F same story 40 degrC/ 104 degr F.

Then my idea is to give tires a pressure so that temperature in tire stays 15 degr lower in tire for the ambiënt temperature.

When hot outside you dont have to take a rest , to let tires cool down, if you keep a lower speed, so tire-material produces lesser heat, by making lesser cycles a second. I am thinking of 50 mph max, anoing for the orhers, but better for your tires.

I estimated the temperatures. in time I mayby have to adjust them, when I get wiser , mayby by what is written in this topic.

[Aussieguy]

If pressure is within operational limits but temp is high

could be a hot bearing sticky brake or other mechanical issue

start by crawling under and feeling the wheel rim...
if RIM is real hot to touch compared to other rims ........ a trip to the mechanic may be in order

[Sunseeker16]

Ive got TPMS on 10 tires. One thing that Ive got used to is not really pay as much attention to pressure gain because it goes up pretty quick as tires get hot and none of the tires increase the same as the mate tire. They seen to reach a balance point. One interesting thing happened going through Ohio. Very hot day, tire pressure was up pretty high. Ran into one of the rain storms that was like driving from dry to wet like a curtain. Air tem dropped quickly and you could tell the rain was really cool. Not long after hitting the cool rain one tire alarmed for a slow leak. Got my attention. Started slowing and watching the pressure and it stabilized. Felt good about keeping going then another alarmed. Shortly after another. The short of it was the tires went from very hot to quick cool from the rain and fooled the TPMS to think there was a leak. I guess they work but are not fool proof.