Tire Pressure Question

[HJ Rosch]

I am trying to pay attention to my tire pressures as I drive around the country and seem to have an issue with my inside dual tires. I have a 2018 Alante 31V on a Ford F53 18,000 pound chassis. The recommended PSI for all tires is 82 but I set them at 84 and double check with an accurate tire gauge. I have a Tire Minder monitor that rarely reads what the gauge shows but is fairly close, within a couple of pounds, when cold. My issue is after driving many miles I get a high pressure warning from the monitor ONLY on the inside dual tires at about 101-103 PSI. The tires have a rating of 120 PSI max so I am not overly concerned. The other tires will be around 97-98 PSI. Is this normal? Is there anything I can do? I just don't like the beeping of the monitoring system all the time. I have stopped and checked the PSI with the gauge and it reads 101-103 also. Your input would be helpful.

[Vicr]

Is there any irregular wear to the inner duals?

[RogerR]

You may have a set up that puts more weight on the inside tires.

Consider having the axles looked at by a really good shop.

[Grumpy]

Originally Posted by HJ Rosch

II have a 2018 Alante 31V on a Ford F53 18,000 pound chassis.

Did you buy it new? Have the tires been rotated? They always say that duals need to have all 4 changed at the same time to allow for even wear. That is one reason most don't recommend rotation. If the two front are moved to the rear outside they can be a slighly smaller diameter and put more weight on the inside tires.

[hawkster]

Originally Posted by HJ Rosch

I am trying to pay attention to my tire pressures as I drive around the country and seem to have an issue with my inside dual tires. I have a 2018 Alante 31V on a Ford F53 18,000 pound chassis. The recommended PSI for all tires is 82 but I set them at 84 and double check with an accurate tire gauge. I have a Tire Minder monitor that rarely reads what the gauge shows but is fairly close, within a couple of pounds, when cold. My issue is after driving many miles I get a high pressure warning from the monitor ONLY on the inside dual tires at about 101-103 PSI. The tires have a rating of 120 PSI max so I am not overly concerned. The other tires will be around 97-98 PSI. Is this normal? Is there anything I can do? I just don't like the beeping of the monitoring system all the time. I have stopped and checked the PSI with the gauge and it reads 101-103 also. Your input would be helpful.

I'm running the same chassis and run tires at 86 psi. Have only measured front tires hot with gauge and the pressure climbs quickly after just a few miles. You're well within the tire pressure limits and realistically 5% difference max. I would call the monitoring system people and see if they can do something about beeping (recalibration or software update) or turn it off.

[Foretm]

HJ - I see the same issue on my '19 Entegra Vision 31V. My inner duals are hotter than my outer duals. I can say that the max PSI is the cold pressure so you're well within pressure range, so nothing to worry about there. I bought mine new, so all tires should be the same age/wear. I'm seeing no abnormal wear on my inners. I run mine at 90 but i'm thinking about backing the rears back down to 85 as i didn't see much handling difference and it will make the ride a tad smoother.

[RVermont]

Not sure what your tires are but Michelin has a great rv tire guide that explains quite a lot related to tires used on RV's

The 10-15 psi increase is normal for increased psi related to cold vs operational readings. They state the maximum cross axel difference should be 5 psi cold and 2-3 psi during operation.

I would go back to specified psi and see what changes if you start there.

I get higher pressures and temperatures on my inside tires and always chalked it up to restricted air flows and heat from the underside of the truck, exhaust,engine and transmission. Normally about 2-4 psi difference.

[norty1]

Do you have the ability to change the alarm parameters? Seems like bumping it up 5 or 10 degrees might solve the problem.

[jadatis]

How did you determine the 82 psi all around, was this on a plate somewhere , or did you look it up in a pressure /loadcapacity list.


I can calculate a save pressure for you, if you give me GAWR's or better real weighed axleloads , or better even axle-end loads, weighed in the loading you drive with, so all the persons and load in it.


Then need at least from tires the sises to determine 3 things I need
1, maximum load or loadindex for single load and dual load.
2, reference-pressure , your already given 120 psi.
3, speedcode or maximum speed of tires, probably 120kmph/75kmph is speedcode L.


Can be that if you looked in a list, you looked in the single load list for behind too, and this gives to high loadcapacity for duall load.


By the roadcurve, the inner tires get more deflection then the outer tires on a dualload-axle as you have. some roads have more roadcurve then others.
More deflection means more heatproduction so higher temp of gascompound in the tire ( mostly air but sometimes more Nitrogen).
Higher temp gives higher pressure .
I once suggested to give the outer tires a bit higher pressure to lift the inner tires a little , so more even temp in tires.
Almost got banned from the forum for it.

[HJ Rosch]

Great input from all of you. A bit more data;
1. I bought new December 2017.
2. Tire code shows manufacture date of 2217 on tires.
3. I have 11,000 miles on the tires/coach.
4. I have not checked the wear on inside vs. outside tires.
5. The 82 PSI comes from the coach spec plate
6. The tire max rating is 120 PSI
7. I will try to set the alarm code to a bit higher PSI
8. The PSI left and right do run pretty even when under way. Both outside tires run at about 98 PSI and both inside at 101.

My gut feeling from what you are all saying is this is probably normal for inside tires. I will keep an eye on them as I travel another 10,000 miles to Alaska and the Midwest this summer.

Thanks for the quality responses.

[GMan215]

Increased inside dual air pressure is common. This is due to a decrease in heat dissipation to the inside dual because of decreased air circulation and the additional heat from the brakes. You might want to look at Crossfire (Crossfire - Dual Dynamics). This will help maintain equal pressure in both tires. You can read the specifics on how the system adjusts for variations in tire pressures between the two tires. It's also nice because you can fill both tires from one valve.

[mkassab]

Originally Posted by GMan215

Increased inside dual air pressure is common. This is due to a decrease in heat dissipation to the inside dual because of decreased air circulation and the additional heat from the brakes. You might want to look at Crossfire (Crossfire - Dual Dynamics). This will help maintain equal pressure in both tires. You can read the specifics on how the system adjusts for variations in tire pressures between the two tires. It's also nice because you can fill both tires from one valve.

Agree with GMan on Crossfire..... here's how I installed them.... Link: https://www.jaycoowners.com/forums/f...34g-81805.html

Mark

[craigav]

I am curious as to the thought of having the outside tires at ~2psi higher (cold) to even them out (hot) while traveling? Seems that in having a couple more psi (cold) would work better to distribute the load across all of the rear axle tires when traveling.

[GMan215]

I should have mentioned in my earlier post that using a system like Crossfire does have some limitations. The big one is that you cannot attach a TPMS system to the single valve stem and expect it to provide you with completely accurate pressures. In the event one tire begins to leak slowly or rapidly when the pressure of the system differs by a fixed percentage from the other tire, the second tire will be protected by a safety valve to prevent the loss of both tires. As an example, if the inside dual loses pressure the valve will close and prevent the outside dual from also losing tire.

With a TPMS attached to the now single valve stem it may still show you adequate tire pressure when your inside dual is actually flat. IMHO, go with a TPMS system (TST and TireMinder are both comparable, but TireMinder is less expensive - $299 for a 6 tire system, but can monitor up to 20 tires simultaneously and added or swapped between up to 4 vehicles). These units also provide you internal tire temperature. TireMinder has preset limits for high and low air pressure and temperature.

As a side note, when I had my oil changed in Colorado last summer the shop checked all air pressures and inflated all the tires to 100 psi when the manufacturers recommendation is 84 psi. The reasoning? "We always put 100 lbs. inf RV tires."

[jadatis]

When outside duals 2 psi higher, a bit more weight on outside tires, but roadcurve stays the same.
So then also inner tires a bit less deflection, so lesser weight on them.
I think then still higher temperature in inner tires, but less difference.

External factors like severe braking, wich heat up the inner tires more, still stays.

So I think you are doing nothing wrong to laws if nature with the 2 psi higher.

Has anyone noticed higher temp on outer tire, on the side the sun shines?

[Rico 1967]

I have Tire minder and have many issues with it. I have a friend who has been an R'ver for over 25 years and has never had any tire monitoring devices. I'm considering disconnecting all mine. With all the trucks on the roads and never seeing any monitoring systems on them one has to wonder do we really need these devices or is it just creative marketing?

[GMan215]

It's true that there is no perfect TPMS. The only reliable method is quality tire pressure gauge and the discipline to check all of your air pressures every day (twice a day is better). But remember, tires must be check when cold. This means before you start out on the road. It does no good to check your pressures when you are at the fuel pump. The tires are probably too hot (unless it's winter). It may take several hours for the tires to cool down enough to get an accurate temp.

As a retired Lieutenant of a Truck Company, I can tell everything on that vehicle was checked twice a day - day and overnight shifts. Most people are not diligent enough to do that without a reminder. TPMS should never be a substitute for good old preventive maintenance. Always be ready.

Semper Paratus

[HJ Rosch]

In 2019 I entered the original post on this thread regarding tire pressure. Like Norine I have a Tire Minder system installed on my RV and toad. It has never worked correctly, I have had it replaced under warranty and it still is totally unreliable. I do still use it but only as a poor reference as I check my tires regularly manually. It will be useless for a blowout and is so far off on regular pressure monitoring that I doubt it will notice a slow leak. That’s my rant on Tire Minder!

[psw757]

TST 507 is the way to go for TPMS. Have had ours for 7 years now and accurate.

[Foretm]

I love my TST 507, works great.... to me cheap insurance. Just the other day, I saw a brand new $.5M Class A dragging a brand new Ford F150 platinum on the rim after he blew past me doing about 80 and didn't realize he had a flat on his truck. About a mile down the road he was on the side of the road with a mangled heap of a rim. Close to $600K rig and seemingly no TPMS... not sure if he had one and it malfunctioned or if he never had one to start with. I installed mine immediately after buying my rig...