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My take on how to treat MH tires


scouserl41

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Very well done !!

The only thing I do differently is that I use the cheap flexible cutting boards under the tires when parked for a while. Michelin recommends putting something under the tires as well as covering them so I do.

 

My rear inside duals were impossible to check or air with any gauge or chuck without some sort of extender. My rig came from the factory with flexible extenders (or they were added by the dealer - we bought it new) and they worked - sort of - but I have had a bad experience with flexible extenders in the past so I had DuallyValve extended metal valve stems added. These replace the existing valve stems and require dismounting the tire. They are not cheap but made it so much easier to add and check air that I was very happy I got them. See DuallyValves

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The air pressure stated on the sidewall is not the maximum air pressure, it is the minimum air pressure required to support the maximum load as stated on the sidewall. That is a fact from rvtiresafety.com

the author of the blog is a retired tire design engineer, his screen name is tireman9.

There is a widespread misunderstanding about tire pressure charts. They reflect the absolute minimum air pressure for the corresponding load, not the optimum. The RMA = Rubber Manufacturers association published a pdf for tires, CH 4 pertains to MH tires, pg 51 states to never run less than the air pressure listed on the tire placard in the MH. That is also on the Michelin, Goodyear, Firestone, and other major truck tire websites.

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Ray makes a good point. RVSF has for years said to use the inflation charts, plus 10% for a margin of safety. The lower internal pressure does make for a better ride but too low can cause uneven tire wear and a host of other problems if far enough off. Too high an air pressure will cause the center of the tread to wear faster than the outside and effect handling because the sidewalls won't flex and the tire footprint will be less due to the edges not touching properly. Proper tire inflation plays an important part in safe handling, a comfortable ride, and in tire life. An over inflated tire is more likely to be damaged when it strikes debris on the highways.

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Kirk, what the RMA is saying to NEVER run less than vehicle tire pressure placard (if the owner is still running OEM size tires). IMO, those load/inflation charts are the root cause of many tire failures simply because the users do not know the full facts. FWIW, Michelin, Goodyear websites state the same admonition.

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Kirk, what the RMA is saying to NEVER run less than vehicle tire pressure placard (if the owner is still running OEM size tires). IMO, those load/inflation charts are the root cause of many tire failures simply because the users do not know the full facts. FWIW, Michelin, Goodyear websites state the same admonition.

My post was in agreement with yours. :)

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RMA is saying to NEVER run less than vehicle tire pressure placard

If the tire manufactures are saying the same thing. Then why do they even bother to have those Charts made up for different PSI for different weights?

 

I use those load/inflation charts and add 15 PSI. That has worked with my 10 year old G670's with no problems.

 

Good Year says for RV tires:

How much air is enough?

The proper air inflation for your tires depends on how much your fully loaded RV or trailer weighs. Look at the sidewall of your RV tire and you’ll see the maximum load capacity for the tire size and load rating, as well as

the minimum cold air inflation, needed to carry that maximum load. (See load inflation charts on pages 9–11.)

 

Doesn't say anything about putting the PSI to what is on the sidewall of the tire or placard in the RV.

 

Also for long term storage put a extra 20% of air in the tires then you normally use. Just don't put more in then what your rims are rated for.

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If the tire manufactures are saying the same thing. Then why do they even bother to have those Charts made up for different PSI for different weights?

 

I use those load/inflation charts and add 15 PSI. That has worked with my 10 year old G670's with no problems.

 

Good Year says for RV tires:

How much air is enough?

The proper air inflation for your tires depends on how much your fully loaded RV or trailer weighs. Look at the sidewall of your RV tire and you’ll see the maximum load capacity for the tire size and load rating, as well as

the minimum cold air inflation, needed to carry that maximum load. (See load inflation charts on pages 9–11.)

 

Doesn't say anything about putting the PSI to what is on the sidewall of the tire or placard in the RV.

 

Also for long term storage put a extra 20% of air in the tires then you normally use. Just don't put more in then what your rims are rated for.

Goodyear RV tires webpage states: " Tire pressure should never be reduced below the vehicle manufacturer's recommended levels to support load conditions in order to improve the ride quality of a vehicle. The difference in ride quality is not significant."

If you wish to browse the Michelin website, it has almost the same statement.

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When I was a young man (boy does that make me feel old) My Uncle, worked for B.F. Goodrich Tire Co. at the Pico Rivera Ca, Plant. He went to work there just out of High School and worked there until they closed the plant in 1975. He always told me to put whatever psi that is listed on the side of the tire. If the tire says to put 80psi in it, I do that. On my RV I have Michelin Tires,they call for 80psi, and on my P/U Truck B.F. Goodrich they call for 80 psi. When I bought my RV it had Michelin Tires and when I bought my P/U it had Goodyear Wrangler Tires on it. I have had great luck doing that. I have also gotten great mileage out of all the tires.

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Goodyear RV tires webpage states: " Tire pressure should never be reduced below the vehicle manufacturer's recommended levels to support load conditions in order to improve the ride quality of a vehicle. The difference in ride quality is not significant."

If you wish to browse the Michelin website, it has almost the same statement.

 

 

My wife and I were going to go on a trip last October so I took my RV into a Tire shop and asked the man working in the service bay, if he would check the air in my tires, (I didn't have my Tire Gauge with me) He did and I slipped him a $5.00 tip. Before I got on the freeway I realized that I had left something at the house. So we drove by our house. I went in and got the item, sitting on the table in the kitchen was my mechanical Tire Gauge. (I always used it in my Semi Rig). We got to the first stop where we were going to spend the night. next morning I got up and we were going to continue on. I walked around the RV checked the Oil, made sure the propane was shut off, did a daily safety inspection as if it were my Semi. I got the tire gauge out and check the dual rear tires, There was 55 psi in all of them. I had specifically asked that he make sure that all tires had 80 psi. in them, this clown made sure that all of the tires had 55 psi in them. Needless to say I will not go back to that tire shop ever again. So now I check my tires myself, I do not let anyone do it for me. I want 80 psi and I will make sure that is what they have. i have a compressor that will put out 175 psi. I also have a 12v compressor that will put out 150psi. You can't trust anyone. Even the folks that are supposed to be professionals.

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Good thread, and nice blog. The more we know and understand how to take care of our tires, the safer we, and those on the roads around us, will be.

 

A summary of my thoughts:

-Have the right tire on your rig. Know our weights, and ensure that you have an appropriate load rating range of your rig.

-Ensure that our steers, are appropriate to be used as steers

-Four Corner Weight - And tire manufacturers recommended PSI fro that weight. (I add +5PSI to to that. And if close to the upper range of the table, I bump up to the next higher level.)

-Keep properly inflated, and I recommend TPMS systems

-Keep clean and protected. (Wheel covers, Aerospace 303, Sunblock, or other appropriate protection.)

-Keep exercised. Get the coach out for a full system, and tire, exercise at least once every 4-6 weeks. Get everything up to temperature.

-If parked for long periods of time. Raise PSI to the highest allowed for that tire/wheel combo

-If you have levelers, put them down enough to get some weight of the tire

-Yes to parking on a protected barrier from the ground

-Inspect regularly

-If over 5 years of age, go have an annual dismount and inspection performed at a qualified tire place

 

Practice safe tire maintenance, and your tires should take good care of you!

Best to all,

Smitty

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Good thread, and nice blog. The more we know and understand how to take care of our tires, the safer we, and those on the roads around us, will be.

 

A summary of my thoughts:

-Have the right tire on your rig. Know our weights, and ensure that you have an appropriate load rating range of your rig.

-Ensure that our steers, are appropriate to be used as steers

-Four Corner Weight - And tire manufacturers recommended PSI fro that weight. (I add +5PSI to to that. And if close to the upper range of the table, I bump up to the next higher level.)

-Keep properly inflated, and I recommend TPMS systems

-Keep clean and protected. (Wheel covers, Aerospace 303, Sunblock, or other appropriate protection.)

-Keep exercised. Get the coach out for a full system, and tire, exercise at least once every 4-6 weeks. Get everything up to temperature.

-If parked for long periods of time. Raise PSI to the highest allowed for that tire/wheel combo

-If you have levelers, put them down enough to get some weight of the tire

-Yes to parking on a protected barrier from the ground

-Inspect regularly

-If over 5 years of age, go have an annual dismount and inspection performed at a qualified tire place

 

Practice safe tire maintenance, and your tires should take good care of you!

Best to all,

Smitty

You have fallen victim to those load/inflation charts, which BTW, show the absolute minimum air pressure, not the optimum. Re-read the link from the RMA I posted, then read the Michelin and Goodyear websites, which contain the same information. You are trading tire safety for a comfortable ride.

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RayIN - I respect your right to have a different opinion then mine, and others whom own RV's. But, I'll keep doing what I'm doing, at the recommendation of the tire manufactures. (I've mentioned in other threads where you have also commented as above, that I called and talked with tech support of two different tire manufactures about how to use their Load Inflation to PSI tables in regards to my RV tires. Both confirmed that their Load Inflation to PSI tables were accurate for RV application too. I called them specially to find out if these charts included a safety margin of some kind, like for extended periods of driving with heavy cross winds loading the leeward tires. Both said yes, both declined to say what and how the safety margins were calculated. Thus my extra 5 PSI, and if within the top say 25% of a range, my decision to bump up to the next higher load rating line and using that PSI. So keep in mind, all of my threads are not running at 'the absolute minimum'.

 

But, I encourage all to make their own decision, and do their own research.

 

I also recommend reading Tireman9's threads on many boards, and his blog too. He has good sound info, and solid links to even more info:)! (And note to those who may go read Tireman's Blog. He recommends not an extra 5 PSI, but a percentage above the tire charts PSI value. I did the math, and due to my always bumping up to the next weight level on the inflation chart when within 25% of the range, and then adding 5PSI to that, that my running PSI is within the range that Tireman9 recommends. I just came at it a different way:)!).

 

http://www.rvtiresafety.com

 

As on other boards, I feel I'm doing what is right for me. You can continue to share your thoughts, but as on other boards, I find your posts to be condescending in regards to your opinions on the use of Load Inflation Charts. Not just to me, as in 'You have fallen victim to those load/inflation charts'... But to many other members on different forums too. But again respect your choice to run the PSI at the higher levels you feel is right, and safe for you. And, I believe you are doing this out of concern for others - so best to you.

 

Smitty

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Smitty, what is your opinion of the RMA statement about never running less than mfgrs. tire placard pressure?

What is your opinion of the Goodyear tireinflation/loading statement: "Tire pressure should never be reduced below the vehicle manufacturer's recommended levels to support load conditions in order to improve the ride quality of a vehicle. The difference in ride quality is not significant. When minimum inflation pressure requirements are not met, tire durability and optimum operation can be affected".

Those are not my opinions, they are statements of a fact from Goodyear and the RMA- governing body.

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Hi RayIN - First, I should have sent you a PM instead of posting my feeling you were condescending in your post. My apology to you for not doing so.

 

We'll I'll tell you, my year CC was shipped with Toyo tires. Nothing wrong with Toyo tires, the tires that then National Owned CC (and my understanding was that National was calling the shots) were not appropriate for the coaches. Same can be said for the Koni SP1 Adjustable shocks that were not able to handle there front IFS on these coaches. (And, Koni told them this and recommended against this shock on these coaches.) So when I read a now 11-12 year placard on my coach, I take I consider it, but take it with a grain of salt. My coach was built in September of 2003, and my documentation all says to run old Diesel Type 2. Things change, for example, now it's ULSD, so the manufacturers documentation is inaccurate.

 

RMA changes their recommendations from time to time too, as do the tire Manufacturers. So 'printed' documentation does change, and become obsolete. And to be fair, my call to specifically Michelin about 5 1/2 years ago now on the 'then load inflation charts' in regards to the XZE* tires, may get different 'Tech Support' answers today, then I received back then.

 

I stand by my feelings that what I'm doing is safe, and is in the guidelines of Michelin and now BF Goodrich (Michelin) in how I'm determine and maintaining my tires PSI's. I have a safe PSI, with a good margin of safety on the top side, for my weights and tires combinations. So, I won't rehash it again. Heck, I almost when up a tire size and 2 higher load rating size on my steers - why would I look at an outdated tire placard referencing a CYA PSI setting, for a tire size I'd no longer be running with?

 

You and I both reference Tireman9's site. He does a great job on helping us all without his experiences, understand an important safety item like tires. He has also recently personally tried to help me sort out the unusual/conflicting info I received from a Michelin Dealers Tire Manger - an expert I went to for help due to some bulges from result of a pothole encounter.

 

Does he not also recommend using the Manufacturers Tire Inflation charts, again appropriately trying to educate (as you are too) that these are 'minimum' PSI recommendations, plus a percentage above this PSI as a safety edge/contingency?

 

My best to you, and again sorry if I was too thinned skin on how you responded to my post on using the Inflation Charts,

Smitty

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In general, Motor Home (MH) tires seem to be a mystery to the owners. Sometimes to much is read into information provided by tire manufacturers for such vehicles.

 

Clearly, the fitment regulations for tires fitted to Motor Homes are from Federal Motor Vehicle Safety Standards. More specifically, 571.120 and others referenced within 571.120.

 

Tire fitment sizes, their load capacities and recommended inflation pressures are not arbitrary. They are selected by the vehicle manufacturer because they are appropriate for that fitment.

 

Tire industry standards do not recommend using any tire inflation pressures less than what has been recommended by the vehicle manufacturer and placed on the vehicle certification label.

 

Footnote: Sometimes FMCSA regulations get mingled with FMVSS regulations in relationships with MH tire fitments. Regardless of a tire’s basic design it must be fitted in accordance with FMVSS when fitted to MH axles.

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This is one of those items where people can get hurt, the owners of a coach, and those around them too. Tires are one of the most important safety items on a coach. I agree that many owners are not up on tires. And in general, those that are not so, should follow the placard and coach manufacturers guidelines.

 

That being said, I still believe that with proper research, and guidance from tire professionals (with big truck/RV experience), that it is safe to change from the OEM's trie size recommendation and inflation placard.

 

I'll repeat that with direction from then owner's National, Country Coach put Toyo's on some models of 2003 and 2004, that were not appropriate for the duty. Not a Toyo problem, but it escalated to the point that for awhile Toyo said to not use their tires on RV's. That is a specific example, where the vehicle manufacturer made a mistake on the appropriate tire for the job.

 

I also know that many coach owners have gone from 8.25 to 9 inch wide wheels, so they cold get more tire under their front end specifically. That was also done because some coaches and models left the factory right at the limit of the both the front end weight capacity, and also tire load ratings. Another example where common sense, due diligence, and coordination with in some cases the manufacturers and other experts - yield smart changes to tire sizes, loads, and thus PSI's that differ from the placard.

 

I'm not trying to cause any ongoing debate here, as I agree that in general the manufacturer and placard are the way to go for a great deal of the 'get in and drive' RV owners. Just pointing out that manufacturers make mistakes, and that the owners sometimes need to step in and changed from what was recommended when the coach left the factory.

 

Best to all, and OP, I did like our blog - and have read more then just on the tires and how to treat them:)! I'm done now...

Smitty

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My previous post (#19) was mainly about Original Equipment (OE) tires and who was responsible for their fitments and recommended inflation pressures. I should have pointed that out in that post, sorry.

 

After market - referred to most often as “plus sized” tires - should be selected after collaboration with the vehicle manufacturer and tire manufacturer. The tire industry has procedures for their fitment. Basically they have to be of a size with available load capacity equal to or greater than the OE tires. Their recommended inflation pressures need to be high enough to provide the amount of load capacity - by inflation - of the OE tires. Auxiliary tire inflation pressure labels are authorized by regulation and can be displayed adjacent to the original tire placard.

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What I have read is to have the tires at suggested pressure when cold which is 80 PSI (5.44 atm or 551 kps). The tire pressure monitors note that the pressure can then get in excess of 100 PSI after a few hours of driving. Is this dangerous? We have been doing this for 8 years of full time RV'ing.

Reed and Elaine

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One thing to keep in mind with a TPMS is to follow the "trend" of the tires in regards to their pressure and temperature. You can drive yourself silly watching for changes. There are so many variables that contribute to the changes. Sometimes the road surface is rougher and hotter or the sun might be shining on one side or the other. What you do want to look for is a sudden increase or decrease of pressure. It's sorta like watching your investments. Are you a "day trader" or in it for the long haul? I am very careful when it comes to tired but I also try to use a bit of "common sense" in my monitoring habits.

Your mileage may vary.......

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Hi folks

I'd like to offer some comments on adjusting tire inflation

 

IMO the statements we have all seen from various sources about never changing the pressure from the vehicle manufacturer's numbers are a sign of the lawyers at work. This is nice and "safe" piece of information good for the general public that never checks the air pressure and certainly isn't going to bother to get actual weights or heaven forbid do some basic math and published tables. I feel however that most of the RV owners that follow the various forums want to do a better job than the bare minimum when it comes to maintaining their RV.

 

Lets look at the Michelin RV Guide on pg 4 - 7 we see they cover the process of proper weight and calculation of loads.

 

The top of pg 8 gives an example of how to determin the proper minimum inflation based on measured load and the Load / Inflation tables start on pg 20.

 

Now what about that warning to not inflate to something different than on your sticker?

 

I suggest you read and then re-read the section on pg 4 on "DETERMINING THE RV’S CORRECT WEIGHT" and pay special attention to the mention of inflation.

 

It is important to remember that by law the inflation on the sticker must provide sufficient load capacity to carry the GAWR for each axle assuming a 50/50 side to side split. So if you are significantly under the GAWR then clearly you do not need to run tire pressure needed to carry the GAWR.

 

Note that in this RV tire guide that is intended for the conciencious RV owner Michelin says

"For instructions on how to weigh by wheel position, see next pages 3-5.Once you know total weight and weight on each wheel position, the tire load data chart will show you the correct inflation pressure fo reach wheel position."

 

emphasis added

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