Tire pressure in relationship to tire temp

[jagpot]

OK this is for all you extra smart people out there. Is there a direct relationship between tire pressure and tire temperature? My front tires call for 125 pressure. With less mass hitting the asphalt will the tire temperature go down?

 

[Neal]

I'm not sure you could vary the tire pressure enough that surface contact would change enough to change tire temps. There are multiple factors I can think of that go into tire temps from road temps, ambient temps and possibly axle/brake heat transfer.

 

[jagpot]

I'm not sure you could vary the tire pressure enough that surface contact would change enough to change tire temps. There are multiple factors I can think of that go into tire temps from road temps, ambient temps and possibly axle/brake heat transfer.

Thanks Neal. Good to know. Just left Los Angeles headed for Napannee. I will have them take a look at the axle:brakes

 

[TJ&LadyDi]

OK this is for all you extra smart people out there. Is there a direct relationship between tire pressure and tire temperature? My front tires call for 125 pressure. With less mass hitting the asphalt will the tire temperature go down?

I shouldn’t comment here because I am certainly not “extra smart.” That said, I have had a fair amount of experience with tires, from RVs to auto racing.

Unless your are going directly from a heated garage to a sub-arctic road surface, the tire temperature will not go down. Tire heating is primarily from sidewall flexing, IME. Lower tire pressures allow more sidewall flexing and that creates more heat. And, that’s why it is important to have RV tires properly inflated for the load they are carrying.

Heated air expands in volume and since the air is contained within the tire, this results in higher pressure. Tire pressures are always spec’d as “cold.” This means normal, resting conditions; somewhere around the 60-70 degree range. From a purely physics perspective, I’m sure that there is a “direct relationship” between a given volume of air and temperature. In a contained environment, that would certainly translate into a direct relationship between “tire pressure and temperature.” Please don’t ask me for the mathematical formula for this as I’m certainly not a physicist.

In most RV tires, you will see a 10-20 degree increase in rolling pressure over resting pressure, depending on the ambient temperature.

Are you experiencing a tire pressure issue that prompts your question?

TJ

 

[jagpot]

I shouldn’t comment here because I am certainly not “extra smart.” That said, I have had a fair amount of experience with tires, from RVs to auto racing.

Unless your are going directly from a heated garage to a sub-arctic road surface, the tire temperature will not go down. Tire heating is primarily from sidewall flexing, IME. Lower tire pressures allow more sidewall flexing and that creates more heat. And, that’s why it is important to have RV tires properly inflated for the load they are carrying.

Heated air expands in volume and since the air is contained within the tire, this results in higher pressure. Tire pressures are always spec’d as “cold.” This means normal, resting conditions; somewhere around the 60-70 degree range. From a purely physics perspective, I’m sure that there is a “direct relationship” between a given volume of air and temperature. In a contained environment, that would certainly translate into a direct relationship between “tire pressure and temperature.” Please don’t ask me for the mathematical formula for this as I’m certainly not a physicist.

In most RV tires, you will see a 10-20 degree increase in rolling pressure over resting pressure, depending on the ambient temperature.

Are you experiencing a tire pressure issue that prompts your question?

TJ

Thanks for responding to TJ. When we left the cold inflate on the front tires was 119 spec say can be 125 across the front. We’ve traveled about 180 miles with an ambient temperature of 89. The tire pressure across the front is 148 and the temperature is 149 which sets off my alarms. I don’t know whether I need to reset my temperature settings or even if you can do that. That increase is certainly more than 20

 

[TJ&LadyDi]

Thanks for responding to TJ. When we left the cold inflate on the front tires was 119 spec say can be 125 across the front. We’ve traveled about 180 miles with an ambient temperature of 89. The tire pressure across the front is 148 and the temperature is 149 which sets off my alarms. I don’t know whether I need to reset my temperature settings or even if you can do that. That increase is certainly more than 20

That’s not too far above where I would expect things to be with those ambient temperatures. That said, the 149-degree rolling tire temperature would concern me a little more than the 148 psi tire pressure. I think I would try raising the front tire resting pressure to the max 125 and see if rolling temps come down a bit.

What are the drive and tag tires doing? And, have you done corner weights on the coach? If not, Newmar will do them for you at Nappanee it you ask (there may be a charge, but I don’t think it is that much). I’m wondering if you might be overloaded on the front axle? That might be another reason to increase the steer axle tire pressures to 125 psi.

What TPMS system are you using? I know the temperature alarm settings can be adjusted on the EezTire system we use.

Safe travels.

TJ

 

[jagpot]

That not too far above where I would expect things to be with those ambient temperatures. That said, the 149-degree rolling tire temperature would concern me a little more than the 148 psi tire pressure. I think I would try raising the front tire resting pressure to the max 125 and see if rolling temps come down a bit.

What are the drive and tag tires doing? And, have you done corner weights on the coach? If not, Newmar will do them for you at Nappanee it you ask (there may be a charge, but I don’t think it is that much). I’m wondering if you might be overloaded on the front axle? That might be another reason to increase the steer axle tire pressures to 125 psi.

What TPMS system are you using? I know the temperature alarm settings can be adjusted on the EezTire system we use.

Safe travels.

TJ

When we get to Williams Arizona I will let the tires cool and then check them and bring them up to 125. The drive and tag axles are dual at 100 now and tag at 1:20. We have an extremely Light load. Our TPMS system is brand new and it is Vallor. Have not done counterweights but we will take your recommendation and have Newmar do them.

 

[TJ&LadyDi]

Just did a little quick research and the generally accepted “safe” temperature threshold for truck/RV tires is 190-195 degrees, so you are well within the safe zone at 149. Don’t know if the Valor settings can be changed (I suspect they can, but it may take some special software), but if they can I think I might up the temperature alarm to 160 degrees. That would give you some leeway while still keeping well within the safe zone.

TJ

 

[Sonic]

Yes, tires run cooler at higher pressures, and conversely as we know, underinflated tires run hotter which is the cause of most tire failures. Of course there's a trade-off in ride quality, and it's certainly not a reason for someone to over inflate their tires.

 

[Voyageurs]

Fill when cold, ignore the pressures when they are hot.