Over inflation tire pressures during travel

[mlpeloquin]

Originally Posted by aza

2019 Entegra Anthem -- I know I should find an answer to my question in the forum but can't. My issue is that I inflate my front (steering) tires to the recommended 120 psi prior to making a trip. During the trip (in 60 degree outside air temperature) the pressure in both tires increases to 155 PSI. I can only imagine that the tire pressure at 100 degrees OAT during the summer will be close to 200. Might I experience a blow out due to overinflation?

I don't have time to read through all the responses, but the tires are to be inflated at the coldest time of day. This is, most of the time, early morning before the sun warms them up. Tire manufactures know about the heating from ambient air temp and from the road driving. The tires are designed for this. The most important thing is to have proper air pressure in the tires at the coldest temps to support the weight on them. Otherwise you are over stressing the tires. Just ask at any tire shop.

[Florida Rang]

I inflate my tires to the Max PSI printed on the sidewall in the early morning before daily temp gets hot. I have been doing this since 1970 when I bought my first Class “ A “ Travco Motorhome. Works for me , so I just keep doing it. If the tire wants to heat up 10 lbs so be it...

[Bobgrove]

Originally Posted by aza

2019 Entegra Anthem -- I know I should find an answer to my question in the forum but can't. My issue is that I inflate my front (steering) tires to the recommended 120 psi prior to making a trip. During the trip (in 60 degree outside air temperature) the pressure in both tires increases to 155 PSI. I can only imagine that the tire pressure at 100 degrees OAT during the summer will be close to 200. Might I experience a blow out due to overinflation?

g



Go to the Michelin website to see the tire charts. It all based on weight of coach at each axle.
There are cat scales all over. I also use a TPM that reads pressure and temperature.
See the charts for at least references.
They even have printable illustrations to record your weights and determined pressures for record keeping in your coach. It's all based on cold pressure no matter where climate. If you notice NO tire tells you max pressure HOT. Also if you notice there is safety factors built in.
I hope that helps.

[Jmclaurin]

Hi, I learned the hard way that you need to weigh your coach. Fully loaded...weigh the entire coach, back axle, and front axle. Then using the chart for your specific brand and tire (which your tire dealer has if you can’t find it online), determine the proper PSI based on your weight.

My tires had a higher “recommended” tire pressure that became dangerous once the tires had heated up through driving. The tires crowned and led to a lack of steering control.

Safe travels.

[FL420]

Originally Posted by wolfe10

Sorry, this is incorrect.


Cold is "before driving at current ambient temperature". PERIOD.


You will not find a single tire manufacturer that says XX PSI at YY ambient temperature.

Well, both of you are right but it's more complicated than you are presenting. I have read that most (not a legal requirement AFAIK) tire manufacturers work with vehicle manufacturers to test their tires on new vehicles to determine which tires will be offered as OE on the new vehicles. They also determine the load ratings, tire pressures and GVWR of the vehicle on that tire which will be displayed on the door jamb or door sticker.
One of the tests which is required by federal regulation measures forces on the left front steer tire in a right turn at 60 mph. I haven't been able to pin down all the other test points but I have read several years ago that the pressure in the tires is measured at a temperature standard of 70°F. If you look carefully at the OEM temperature vs. pressure table below you will see that the temperatures start at 70°F and the pressures in the columns increase by 1 psi for every 10° decrease in OAT up to 65 psi and above where it increases by 2 psi per 10°F decrease in OAT down to 40°F when the pressure increases level off.
https://www.caranddriver.com/news/a1...ssure-matters/
[emoji40]

[Mallie]

We ask this question At our a rally, Michelin rep said never check on the road unless you have reason to suspect low. The pressure will scare you.
As far as rated pressure, the max allowable on the tire will give you the best performance.
Any flex, adds to the heat. Heat will kills a tire before pressure.

[jadatis]

Originally Posted by jadatis

F. / PSI
7 / 105
18 / 108
30 / 111
42 / 114
53 / 117
65 / 120 advice-pressure
77 / 123
88 / 126
100 / 129
112 / 132
123 / 135
135 / 138
147 / 141
158 / 144
170 / 147
182 / 150
194 / 153
205 / 156
217 / 159
229 / 162
F. / PSI

Made this list to show that pressure rising is related to the temperature in the tire.

What they always write is max 120 psi ( cold)
And the pressure rising is taken into account by the tiremakers.

When driving 50/55mph at ambiënt temp of 65 degrF, temp in tire will rise to about 110/115 degrF, when no external factors, like sunshine on tire, or severe braking( when descending mountains fi and using brakes to often). Incidentially temp in tire can rise to boilingpoint of water of 212 degr F.
Your 120 psi would rise to 132 psi.
Your 155 psi means a good 200 degrF in tire.
So if no external factors, pretty hot, and could mean you need even higher pressure then 120 psi cold measured. Not allowed anymore, but then better upgrade tires to higher maxload, or reduce overload.

Once read that tires are designed to stand 2 times reference-pressure , your 120 psi that is 240 psi.
Maybybin these high pressures less, but then still the 155 psi would not be a problem.
The temperature in tire though is related to the temp of rubber of tire, and the temp can be a problem.
To hot rubber makes it hard and crackes are formed, wich dont go away and get larger in time, whatever you do afterward, until at some moment the tire suddenly blows or treath-seperation, with the missery that goes with it.

In adition to my first post here next.

Assume your 120 psi cold is the right determined pressure for your front tires, you fill them cold on an average ambiënt temp of 65 degrF.

Now later on a cold day 42 degr F you measure cold 114 psi . Action : leave it , dont chanche the pressure. Cooling down and heating up of rubber of tire is still in balance so rubber wont overheat. You may fill up to 120 psi for roadhandling, but for savety of tire not needed, and it spares you to let off air when on a hot day.

Now on a hot morning 88 degrF, you measure cold pressure of 126 psi. Action : leave it , dont chanche the pressure. Cooling down and heating up of rubber of tire is still in balance so rubber wont overheat.

Now when driving on a average ambient temp of 65 degrF , about 50 to 55mph , yout TMPS system gives 132 psi. Temp in tire then is about 112 degrF, and with that a bit less deflection, so heatproduction a cicle.
Action : leave it , dont chanche the pressure. Cooling down and heating up of rubber of tire is still in balance so rubber wont overheat.

Now on that same drive , one tire in the sun gives 120 psi, while the other in the shade gives the 132 psi. Action, find a place to fill up the 120psi tire, and check the cource of lower pressure and solve it.
The 120psi warm then gives more heatproduction a cicle then the cooling down can handle, so temp of rubber can go at your speed to above critical temp.
You can drive with a lower speed to find a place to check, then because of lesser cycles a second , lesser heatproduction, so most likely rubber does not reach its critical temp.

[SnowNCycle]

I have often wondered that as well.... I have an ARIA 4000 and have wireless monitors/alarm system on tires; temp and pressure. I have to start out in cool 55-60 degree mornings at an "alarm initiating" 110 PSI, so tires hover at 125-130 while driving at 80-85 degrees F ambient temp (tires considerably hotter). How much leeway is built into these tire pressures?

[KanzKran]

Originally Posted by Mallie

As far as rated pressure, the max allowable on the tire will give you the best performance.

Beg to differ. My tires have a maximum rated load pressure of 80 psi, the door post says 61 psi front and rear, and I run 40 psi in the rear and 48 psi in the steer tires. That's what corresponds to 110% of actual axle loads, but I am about a ton light on the drive axle, and half a ton light on the steer. At 61 psi, it rode like it was on wooden wagon wheels. I can't even imagine what it would be like at 80 psi.

Granted, it's a van with LT215/85R16 tires (duals in the rear), but someone recently asked about a Class A with tag where tire pressure in the drive and tag tires would be just off the bottom of the chart for those tires. It was too heavy for a single rear axle (over 20k) so it needs the tag, but with two axles, the tires the manufacturer used required very low pressure.

I think front tires were somewhere around 100 psi though, being the same size tire on a heavily loaded axle (from memory). Maybe they weren't the original tires, and the steer tires were supposed to be higher capacity than the rears. But either way, running those rear tires at sidewall pressure would have been like driving on steel railroad wheels, without the rails.

[voltdoc]

According to the Spartan spec sheets the 2019 Entegra Anthem has Michelin 315's. In 2020 I believe they went to the 365's on the Anthem.

Here are the specs for the 315 X Line Energy Z, it has a max load rating of 9090 and a max cold psi of 130 when fitted on 9" wide rims.

https://drive.google.com/file/d/1I4u...w?usp=drivesdk

I have the same steer tires and front axle on my 2017 Entegra Aspire B floor plan. We are full timers and run relatively heavy. Based on actual four corner weights I run 118 cold on the steers and 90 on the drive and tag. A pressure rise to 140-145 on the steers is normal in my experience, but on occasion I have seen higher. I'm using a TST TPMS. I don't worry about the actual pressure reading so much, but mainly that there are no significant variations between the tires.

So the OP's 'recommended' 120 psi is probably not too far off from where it should be but could of course be improved by knowing the actual weights. According to the loading charts in the document below, 120 psi would represent a load of 16540 lbs on the front axle which has a rating of 17000 lbs. 123 psi cold would bring the tire capacity about equal to the axle rating.

Here is the full Michelin RV guide:
https://drive.google.com/file/d/1XxJ...w?usp=drivesdk

[TXduo]

FWIW, I use a gauge to manually check my tires cold before leaving the campsite. Then about 2-3 miles down the road I'll look at the TPMS (a TST-507 system) to verify the pressures. Then I ignore all high pressure readings the rest of the day as this TST-507 system reports my tires have increased to the 400 to 500 psi range. Yes, that is not a typo. Truck Systems Technology has a design problem the lead tech knows all about that causes totally irrelevant psi readings, and even talking with the VP of the company won't fix the issue but he advises to either ignore the obviously false readings or purchase something else. Sometimes this TST-507 will correctly flag a pressure loss (such as when I had an extender spring a leak), but other times it will still report an alarm for overpressure when the actual pressure is 1/2 of the safe psi.

[texasrs]

"change"

[vinni57]

Isn't the tyre info listed on the tyre/ Inflate to ( whatever ) pounds cold?

[TXduo]

By the way, undisputable photo showing TST system indicating false high pressure alerts.

I was at recent rally where a competitor TPMS was replacing batteries for free and when one tire sensor wouldn't come back online, they no questions asked just replaced the sensor for free, even though that sensor was about 10 years old. Shows a different mindset on customer support as opposed to the lack of concern from TST.