Correct Cold Tire Pressure

[mrtravel11]

I have a 2009 40' Monaco Camelot with Toyo tires on it (295/80R22.5). The tires themselves say the Max PSI is 100. That is what I have been setting them cold. Then I was reading that the Max pressure on the tire is not necessarily what you want to set them at. So, in doing research on this, I found many different pressures. In the coach, the plate says the GVW is 37600 lbs and the tire pressure should be 115 psi single front pressures and the dual back should be 100 psi. Yet, information I have from Toyo says NEVER exceed the sidewall markings for maximum loads and inflation pressures (which is 100 psi)
So my question is, what are the proper cold tire pressures for my rig??
What pressures are people setting their tire pressures at for the road??

[96 Wideglide]

Toyo 295/ 80's should have a max psi about 125 psi.

Which model Toyo's do you have?

I run 115 front 85 drive axle and 80 psi tag axle.

[JJTL]

As Wideglide mentioned, first step would be to confirm which Toyo tire you are running. We just installed Toyo M144 tires a few months ago and love them.

Here is the manufacture link for the Toyo M144: https://www.toyotires.ca/tires/premi...ial-m144a-m144

100psi seems low for your size tire, max inflation. The max inflation pressure on the Toyo M144s depends on size, but for our tire which is same size as yours it is 125psi cold (295/80R22.5).

Tire inflation should be set based on the weight of YOUR specific coach, as equipped and loaded to go down the road. This is best achieved by preparing your coach and then having it weighed at a truck scale. Once you have weighed your coach (preferably at each corner, but can also be done per axle), you use the manufactures Tire Inflation Guide to set your pressures.

Here is the Toyo RV Tire Inflation Table: https://www.toyotires.ca/sites/defau...n_tables_0.pdf

Note that there are different inflation weights/pressures for single wheels (front and tag) and dual wheels (rear).

Hope this is helpful. Let us know if you run into any other questions. Until you are able to complete this exercise, the safest option you have is to run your tire pressures based on your GVW of 37,600 lbs. The 37,600 lbs GVW is made up of a front axle with a max carrying capacity of 14,600 lbs, and a rear axle with a max carrying capacity of 23,000 lbs. Divide these numbers, to see what weight would be at each corner and then reference the Inflation Table. For your front tires you would look at the inflation pressure needed for a single tire carrying 7,300 lbs (14,600/2). For your rear tires you would look for the pressure needed for a dual tire to carry 5,750 lbs (23,000/4). If you do indeed have the Toyo M144 tires, using the max weights above the Inflation Table indicates you should run 115psi on the fronts and 100psi on the rears, this also aligns with your data plate on your rig. More pressure usually means harsher ride, so ideally you would weigh your coach and see if its possible to safely lower any pressures based on your specific weight. Hopefully you're below GVW to begin with, always good to check that from time to time. Also note that tires on the same axle should always be inflated to the same pressure (based on the heavier weight).

[jadatis]

The intention of the institutes that give your pressure-advice, is to be in the clear with mother nature, so your tires wont fail in time.
But the different advices are because they all have different ideas of how to achieve this.

I claim to know how it works, call myself " pigheaded Dutch selfdeclared tirepressure-specialist" .

And best is to weigh fully loaded , as you go on tripp, so also water and all the persons in it, and best per axle-end, second best per axle.

But practice is , that this is not that often done, then should we do with no advice? No, as long as not weighed, we have to do with the Gross Axle Weight Ratings ( GAWR) , this is maximum allowed weight on the axles, and we assume you are not allowed to overload vehicle and seperate axles.

Already given here are the GAWR's and GVWR .
Mostly GAWR's together are a little bit more then GVehicleWR, but here exact the same, this means, you never can use GVWR totally, because weight is never devided that GAWR's are used up totally.

Advantage of such a heavy motorhome ( in the eyes of this European ) , is that you mostly stay below GVWR, but no guaranty.

Once you determined the weights, and have the right data of your tires ( look again on sidewall, 100psi must be wrong) , I can put it in my made spreadsheet, and give highest pressure advice, with maximum reserve, with still acceptable comfort and gripp.

Filling in the GAWR's would likely still give some bumping, but certainly safe for the tires ( because real weigt is most likely lower....ooh dangerous statement) , and lifetime if tires up to 10 years.

Did this on mobile phone, so sorry for writing- errors.
Spelling can be wrong to, because English is not my native language.

[blahargoue]

100 psi max pressure on your tires indicates to me that at some time somebody installed under rated tires on your rig. You should read the weight ratings stamped on your sidewalls and make sure that the tires are rated to support the weight of your rig.

[rlott2k]

I suggest confirming the 100 psi max inflation.
If your sure of that I would change the tires,as they are insufficient for your rig.

[K7JV]

JJTL, I think you offered the best overall discussion on tire pressures I've ever seen. Well done! I'm going to copy it and keep it.

Just as a comment, a wee bit off subject, the one thing that scares the begeezes out of me is when I inflate a tire to 115 PSI cold (per virtually all guidelines), where the tire is rated for, lets say, 120 PSI cold (per the manufacturer), and then you glance at the pressure on your tire monitor while you're going down the highway later that same afternoon and you see that the tire is actually running over 130 PSI, it's a bit unnerving! It's all in the definition of "cold". I'd love to see a chart or table that defines "cold", when it comes to setting tire pressures.

Also, I try to never adjust my tire pressures when some are in the sun and some are in the shade, or at the end of a run while they are still warm from the trip. I prefer to do it in the cool of the morning, while the tires are still in the shade.

I personally think a good tire pressure monitor system is a must, on an RV, and on the towed vehicle, too. It is my practice to use a gage to test pressures only when I am making a change. Every time the Schrader valve is disturbed, the chance for a slow leak is created. It's kind of like the adage that says, "If it isn't broken, don't fix it." So I do check my pressures fairly diligently, but I routinely do it with the TPMS. And I don't adjust anything, unless I'm starting to get out of balance left to right on an "axle", or more than maybe five pounds from my desired pressure on any one tire. Then when I do adjust the pressures, I am very careful to do my best to adhere to the principles in JJTL's discussion.

I don't ignore my tires, by any means. But I also don't get overly anal over a pound or two of pressure differences, here and there. If I want to see how quickly everything can get out of whack, all I need to do is check my pressures after I've run a hundred miles or so down an even-numbered Interstate highway with a bright sun in the south, and see how the numbers work out. Not only that, the crown of a highway will shift several hundred pounds towards the passenger side of the coach compared to what we see when we weigh our coaches on the scales. So what we do based on the scale weights changes as soon as we hit the road. Just some thoughts to keep me awake at night, right?

[Ljwt330]

Originally Posted by K7JV

JJTL, I think you offered the best overall discussion on tire pressures I've ever seen. Well done! I'm going to copy it and keep it.

Just as a comment, a wee bit off subject, the one thing that scares the begeezes out of me is when I inflate a tire to 115 PSI cold (per virtually all guidelines), where the tire is rated for, lets say, 120 PSI cold (per the manufacturer), and then you glance at the pressure on your tire monitor while you're going down the highway later that same afternoon and you see that the tire is actually running over 130 PSI, it's a bit unnerving! It's all in the definition of "cold". I'd love to see a chart or table that defines "cold", when it comes to setting tire pressures.

Also, I try to never adjust my tire pressures when some are in the sun and some are in the shade, or at the end of a run while they are still warm from the trip. I prefer to do it in the cool of the morning, while the tires are still in the shade.

I personally think a good tire pressure monitor system is a must, on an RV, and on the towed vehicle, too. It is my practice to use a gage to test pressures only when I am making a change. Every time the Schrader valve is disturbed, the chance for a slow leak is created. It's kind of like the adage that says, "If it isn't broken, don't fix it." So I do check my pressures fairly diligently, but I routinely do it with the TPMS. And I don't adjust anything, unless I'm starting to get out of balance left to right on an "axle", or more than maybe five pounds from my desired pressure on any one tire. Then when I do adjust the pressures, I am very careful to do my best to adhere to the principles in JJTL's discussion.

I don't ignore my tires, by any means. But I also don't get overly anal over a pound or two of pressure differences, here and there. If I want to see how quickly everything can get out of whack, all I need to do is check my pressures after I've run a hundred miles or so down an even-numbered Interstate highway with a bright sun in the south, and see how the numbers work out. Not only that, the crown of a highway will shift several hundred pounds towards the passenger side of the coach compared to what we see when we weigh our coaches on the scales. So what we do based on the scale weights changes as soon as we hit the road. Just some thoughts to keep me awake at night, right?

The tires are engineered to exceed the max cold pressure while driving and on hot days. That margin is built into the tire based on the max cold pressure. It is absolutely normal to see pressures rise 10-20# or more when in operation and tire manufacturers design for that increase.



The greater risk for tire failure is underinflation, which could easily happen if one adjusted down the tire pressure, to the max cold level, after having traveled several miles on the highway.

[mrtravel11]

Originally Posted by blahargoue

100 psi max pressure on your tires indicates to me that at some time somebody installed under rated tires on your rig. You should read the weight ratings stamped on your sidewalls and make sure that the tires are rated to support the weight of your rig.

I have gone to my RV in storage to check on the tires only to find out I need new glasses. The sidewall of my TOYO M144's says 125 max psi, not 100. Therefore, I will set pressures at 115 in the front and 100 on the back. Thanks

[wildtoad]

Originally Posted by mrtravel11

I have gone to my RV in storage to check on the tires only to find out I need new glasses. The sidewall of my TOYO M144's says 125 max psi, not 100. Therefore, I will set pressures at 115 in the front and 100 on the back. Thanks

Thanks for reporting back.

[jadatis]

Trew the GAWR's 14600F 23000R trough my calculator , and it gave 129psi F and 115 psi R.
So Front 125 psi ( at 65degr F) would not even give bumping.

Saw in the list that they are M speedrated, so max 130km/81mp/h.

This is if axles used to full GAWR, probably real axleweights are lower, but as long as you did not weigh, you have to be on safe side.
Did not use my determined pigheaded system of lowering the loadindex by 3 steps, to give tire a deflection needed for 99mph/160kmph., then pressure even higher, and certainly bumping when real weights are lower, as I expect. So my advice will likely stil give no bumping, if real weights are a bit lower.

[Happycarz]

My coach, similar to yours, has Toyo M144 tires with max inflation of 125 PSI cold.

I’m running 110 lbs in the front and 100 lbs in the rear, cold.

[mrtravel11]

Hi Happycarz, we met up at Happy Jack / Clints Well last year and you gave me your name. Good to hear from you.
Looking at the plate in the coach, it says 115 in the front and 100 in the rear. That's what I'll be setting them at.
Thanks and maybe we'll see each other up North this summer.

[Happycarz]

Yup, I remember you. I put a thumb drive with all the Monaco wiring diagrams, along with a host of other files, in my truck to give you this past summer. But, I only made it to Happy Jack once.
I have your business card and will call you.

The wall placard is the pressure to run in the tires when the coach is maxed out, weight wise. Weighing the coach at each corner and using the tire inflation chart is the preferred method. Makes for nicer ride also.