Tire pressure maker 120# coach 85#????

[FLYING BUTCH]

Michelin chart shows 22.5 RV tires 125#. Tried to put that in and message comes up on dash over inflated tires. It call for 85#. Really seems odd. I have always ran 120# or so. Anyone have an explanation on this?.

Safe travels all

[R.Wold]

It’s all based on load. Look at your tire size (not just rim size), and actual tire model, and the load charts will give you tire pressures for various weight ranges. The same tire could have an inflation range from 80-125 psi depending on load.

To use the chart you have to have four corner weights, and then use the higher weight for each axle. So if you have 5900 on your drivers side front and 6100 on the pass side front, use 6100. Same with the rears.

I don’t know what is telling you 85 but I suspect it’s a TPMS that has been programmed for your vehicle weight. I would hope so anyway, but the only way you can get it right is to weigh the corners and consult the tables. Pages 12-14 for RV tires, loads, and inflation.

https://www.michelintruck.com/assets...ok_Jan2007.pdf

The diameter of the rim and the markings on the tire do not provide enough information. Just like a modern microwave, there’s more to it than that

This is also good for general tire knowledge and information:

https://tiretraker.com/michelin.pdf

Would this by chance be on a 2020 Anthem? If that’s the case, your factory TPMS is probably a good starting point.

[Gary RVRoamer]

Solid advice from R Wold. In any case, we can't guess which is more correct without knowing the tire size and at least axle weights. And the source of those 85# and 120# psi numbers.

[kb2ztx]

My tires show 120# at max load. Plaque in MH shows 85#. Go with the MH rating.

[Tha_Rooster]

Originally Posted by FLYING BUTCH

Michelin chart shows 22.5 RV tires 125#. Tried to put that in and message comes up on dash over inflated tires. It call for 85#. Really seems odd. I have always ran 120# or so. Anyone have an explanation on this?.



Safe travels all

Do you have aluminum rims? If so what’s there max pressure on rim?

[FLYING BUTCH]

My rims state 130#s. I did the tire chart and it states 125# for RV no difference if on a dual axle or single?? Guess I need to call Entergra. Thanks for input guys.

[R.Wold]

Originally Posted by FLYING BUTCH

My rims state 130#s. I did the tire chart and it states 125# for RV no difference if on a dual axle or single?? Guess I need to call Entergra. Thanks for input guys.

Well first, those numbers are maximums, 130 for the rims and 125 for the tires. They aren’t the working pressures you want to use. If you are getting 125psi from a chart, you are either reading it incorrectly, or looking at the wrong chart.

Ok, so if we are talking about a 2020 Anthem, you probably have these tires, right?

Front tires: Michelin® XZA 365/70R 22.5”

Rear tires: Michelin XZA 315/80R 22.5”

The fist pic below is for your front tires. It doesn’t state pressures for duals because they aren’t used that way. (from page 13 of this: https://www.michelintruck.com/assets...ok_Jan2007.pdf )

The second pic is your rears, used as duals so that’s the line you want to look at. (from page 14 of this: https://www.michelintruck.com/assets...ok_Jan2007.pdf )

Once you know your actual weights on each corner, you can adjust your pressures as stated above. For now, stick with 85psi since that’s what your TPMS wants and was most likely set at the factory. It’s probably close enough for now, and your final working pressures will change depending on how you load the coach. 125psi would produce a harsh ride and probably create other issues.

If the tire sizes in blue above are different from yours, find your tire sizes and proceed accordingly.

Or just call Entegra and they can walk you through it. One you have this down, you’ll find it’s a valuable tool.

[SuperGewl]

Originally Posted by FLYING BUTCH

Michelin chart shows 22.5 RV tires 125#. Tried to put that in and message comes up on dash over inflated tires. It call for 85#. Really seems odd. I have always ran 120# or so. Anyone have an explanation on this?.

Safe travels all

Well, it would help if yo would fill out your Signature with your MH info so we can better help you.
Normally you fill the tires to the MH MFG specs and NOT the tire MFG specs. Between the Chassis and MH MFG they have figured out what the optimum PSI is for that MH when fully loaded. They have worked with the tire MFG to ensure that the tire on the Chassis can handle the weight. Now that being said, the tire they point on can usually handle more weight and more pressure than the Chassis and MH MFG tell you inflate to. The reason is because the tire is made to be used with more than 1 MH/Chassis.
So follow the MH/Chassis MFG PSI rating for inflation which is usually listed on the little placard next to the Pilots seat.

[R.Wold]

I’m pretty sure it’s a 2020 Anthem with factory TPMS and the tires I noted above. Hopefully he will call Entegra customer service and they can set his mind at ease on proper inflation, which likely is 85psi.

[FLYING BUTCH]

I called Entergra and the referred me to Spartan. The guy there told me they got together with Entergra and came up with the recommended 85# rear tire pressure. Guess they know what they are doing. It is just a huge difference between manufacture recommended pressure. Thanks for reply guys.

safe travels

[R.Wold]

Originally Posted by FLYING BUTCH

I called Entergra and the referred me to Spartan. The guy there told me they got together with Entergra and came up with the recommended 85# rear tire pressure. Guess they know what they are doing. It is just a huge difference between manufacture recommended pressure. Thanks for reply guys.

safe travels

The manufacturer, in this case Michelin, recommends different pressures for different loads. In this case if your front axle has around 15,000lbs on it (around 7,500 per side), and your rear has around 23,000 ( around 11,500 per side), then 85 psi IS the manufacturer recommended pressure.

If you access your actual axle loads, and preferably the weight on each individual corner, (either from Entegra or by weighing it yourself) and consult the charts, it should make sense.

As stated by everyone here, 125psi is the maximum pressure, NOT the working inflation for a specific application. Just like 130psi on your rims - it means just “don’t go over this pressure”.

[KanzKran]

Originally Posted by FLYING BUTCH

It is just a huge difference between manufacture recommended pressure.

Not to pile on, but the sidewall pressure is the minimum or design pressure to support the maximum design load for a particular tire, which is right next to it on the sidewall. Actual load being far below that sidewall maximum load means cold pressure can be, and probably should be, far below the sidewall pressure, per the tire load/pressure charts, but usually with a little extra for side-to-side unbalance, and seasonal or locational temperature changes so you're not chasing cold pressures every morning.

[R.Wold]

And put another way, for 125psi to be correct, your coach would have to weigh 72,000lbs!

[Ray,IN]

Originally Posted by R.Wold

And put another way, for 125psi to be correct, your coach would have to weigh 72,000lbs!

I'm not convinced of that. My Winnebago on a Spartan MM GT frame, with a 12,000# Reyco Granning IFS front end calls for 105 psi in LR G tires. Your calculation would have the single rear axle weighing more than the legal limit.