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Old 08-16-2015, 05:35 PM   #1
'11 390BH
 
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tire pressure, am I doing it correctly

Hi all,
I'm excited that I've finally picked up my new coach, a 2011 390bh. I've become increasigly concerned about proper tire inflation so I bought a tpms and had her weighed today with the original 13k mi 255/80/22.5 XRV michs.
Having just picked it up there isn't much in with me besides the usual bedding and luggage, a very few things in the kitchen and fridge. Half a tank of lp, half water, less than a qtr black and gray. 2 kids a dog and 3 avg healthy weight adults.. the basement is virtually empty, 1 factory slide that has maybe 50lb on it. 20lb of other stuff aft of it.

Pictures are attached.of my cat triple scale reading for the coach and toad.

So I'm doing the chart and it looks like I'm already overweight on the fronts.at 5,300lb ??And should have the max 110psi in them cold. Rears should be at 100 but the chart on the wall says 110lb all around?

So if anyone can chime in here if I'm looking at this wrong or I'm over on one, both, or all and should be concerned. Never paid much attention to it in my gasser, had 4 blowouts and don't want anymore. Thanks

http://https://www.dropbox.com/s/kh2...33-21.png?dl=0

https://www.dropbox.com/s/ulil2ipcsc...10.30.jpg?dl=0
https://www.dropbox.com/s/gt32pcxrgx...81333.jpg?dl=0
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Old 08-16-2015, 09:57 PM   #2
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I am not able to open your first and most important picture. We all know the specs just tell us your weight. Also do a search in this topic. It's just not possible to cover the important info on this topic.
The Readers Digest version is there is an ongoing issue with the weight and capacity with some models. You front axle is rated at 10500 lbs. your tires at max inflation is rated at 10400 lbs. obviously you are saying you are over that. You are not alone and there is a fix.
Almost any FL Oasis dealer should be able to contact Gafney service and get the info for the fix. If they don't PM me and I will give you my Vin number and they can look up what they did to fix mine.
What they do is replace the front air bags to bring the front axle up to 12000lbs. I have researched this info and believe it to be true. The only difference between the 10500 and 12000 is the air bags.
You will also need new tires. You can go with 275 80r22.5 or 275 70 R 22.5. Mine was replaced with 275 80 and are Michelins XZE2. A good tire and I'm very happy with it.
Mine was covered under warranty at FR's expense but if you just bought a 2011 I assume it was used so I would not comment or guess as to who would cover this.
I strongly urge you to do this upgrade as running tires over weight for this long can and will cause unseen damage and a blowout could happen. Feel free to PM if you have any questions.
I'm sure others will chime in as several have gone through this.
Oh and congrats on a great MH. This is fixable so don't stress to much.



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Old 08-16-2015, 11:24 PM   #3
'11 390BH
 
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Steer axle - 10,600
Drive axle- 17,840
Tow vehicle' 4380
GCVW-32,820
Phil, thanks so much for this. I'm on the road, searching from this phone is less than fun. This was helpful. I'm headed south from niagra falls to Gaffney late this week so, maybe that's the time to get er done?
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Old 08-17-2015, 04:15 AM   #4
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Have put the data in my calculator and made picture of it.
Also read the extra information below the pressure advice.
But assumed you weighed with all the luggage and persons in it, otherwise your axle weights in use will even be higher.

The front pressure advice gives red in both value and pressurekind, because advice is higher then even American tire makers allow for LT tires .
For Truck tires , wich your tires in fact are, they allow 20 psi higher .

So front 125 psi advice for up to max speed of tire of 120km/75m/h,as I searched back on Michelins site at the specifications.

And rear 113 psi. Here only pressure kind is red because within 10 psi above AT-pressure, wich is not the maximum allowed cold pressure of tire.
For maximum pressure with still no discomfort and still good gripp you can even use higher pressure.
So my advice for the loads you gave is 130 psi front and 120 psi rear , for maximum reserve without bumping. This is what most American tire makers still alow.
But all write that the rimms must be allowed that pressure too, and its given on inside of rimm so you have to get one wheel off or if spare is the same look at that.
What is given is cold pressure , higher pressure by higher inside tire temp is calculated in the specifications.

so my idea is better to use the high pressure , even if rimm does not allow it, better neglectable chanche on rimm leakage then tire damage with blow out and accident and injuries and damage.

Best is still to get new tires and axle upgrade and eventually new rimms , and or do some weight shifting , rear has some reserve, but for now you have to do with the things you have. If you give GAWR's and GVWR , you will see if they have some reserve.

Here the picture.

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Old 09-03-2015, 11:46 AM   #5
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UPDATE**
I'll post another thread on the backstory later, but in the meantime I want everyone's opinion.
I ended up with new tires, airbags, and wheels. The tires are Mich XZA3+ 275/80/22.5 G


My weight hasnt changed
Steer Axle- 10,600 lb
Drive Axle- 17,840 lb
If I look at the load pressure chart for these new heavier duty tires, my pressure should be Front @ 90psi and Rear @ 80psi.

I told this to the guys doing my tires today and they just about refused, telling me that I need to run the fronts at 100psi min, and max inflate the rears to 110psi.

I'm of the mindset, that the engineers at a company like Michelin probably know a lot more about this stuff than the dude behind the counter at a shop, no matter how many trucks hes seen in his time. AM I alone in thinking the load pressure charts exist for a reason and should be followed?? If this were aviation related i would not deviate 1 iota from the manual in black and white.
I told him to set them to 100 all around, that made him happy enough. Would you guys deflate them tomorrow morning to the chart pressure or leave as is???
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Old 09-03-2015, 12:13 PM   #6
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After having the upgraded tires/airbags thing done, I run 100 front and 90 rear.

FWIW, I'd think that FR might foot the bill for this no matter how old the coach is. It could be a HUGE lawsuit against FR if you were to have an accident because they built so overweight.

Mine was not under warranty and they paid anyhow.

Boowho??
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Old 09-03-2015, 12:18 PM   #7
'11 390BH
 
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They did the same for me, except I upgraded wheels seeing the new tires as a winfall on a 4 year old used coach. Terrific service, Randy is the man
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Old 09-03-2015, 12:20 PM   #8
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No way would I listen to local tire guy. It is published in the Michelin guide and that is what I go by. Add 5 lbs as a safety and in case you have guests traveling with you so you don't have to add air.



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Old 09-03-2015, 12:28 PM   #9
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Interesting. Not sure if this effects my coach or not but will look into it.
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Old 09-03-2015, 12:31 PM   #10
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Joe. Call the dealer and see what tires you have on it. If it's 255 start the process before you sign. A quick call to the salesman will get you an answer.



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Old 09-03-2015, 12:38 PM   #11
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Joe. Call the dealer and see what tires you have on it. If it's 255 start the process before you sign. A quick call to the salesman will get you an answer.

Done ! Sent him an e-mail requesting that info.
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Old 09-03-2015, 01:08 PM   #12
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Interesting. Not sure if this effects my coach or not but will look into it.
I sure would, I told the previous owner and he was oblivious to the issue, and he used to run this thing loaded to the gills and I talked to a BerkXL owner recently and he said he never pays attention to tire pressure, weight, or his speed. I want to be as safe as possible. looks like its going to be 95/85psi for me

Some Credit Due to Phil for helping me and others with this. Thanks Phil!
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Old 09-03-2015, 01:57 PM   #13
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Originally Posted by kohersh View Post
UPDATE**
I'll post another thread on the backstory later, but in the meantime I want everyone's opinion.
I ended up with new tires, airbags, and wheels. The tires are Mich XZA3+ 275/80/22.5 G


My weight hasnt changed
Steer Axle- 10,600 lb
Drive Axle- 17,840 lb
If I look at the load pressure chart for these new heavier duty tires, my pressure should be Front @ 90psi and Rear @ 80psi.

I told this to the guys doing my tires today and they just about refused, telling me that I need to run the fronts at 100psi min, and max inflate the rears to 110psi.

I'm of the mindset, that the engineers at a company like Michelin probably know a lot more about this stuff than the dude behind the counter at a shop, no matter how many trucks hes seen in his time. AM I alone in thinking the load pressure charts exist for a reason and should be followed?? If this were aviation related i would not deviate 1 iota from the manual in black and white.
I told him to set them to 100 all around, that made him happy enough. Would you guys deflate them tomorrow morning to the chart pressure or leave as is???
Again with use om my made spreadsheet for these tires, Front 104 psi and rear 94 psi for minimum needed for maximum speed of tires of mostl likely 75m/h.

But highest psi with no bumping F 117 R 107.

So trust the advice of the guys doing your tires , they know that the American made lists give to low pressures.
Strange is that Michelin gives for European tires with same sises and AT pressure ( yours 275/80/22.5 AT 110 psi lower loadcapacity's for the pressures .
So fill at F117 R107 ( make it 115/105) and if in time pressure drops to F104/R94 your tires still wont get to hot if speed is below 75m/h.
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Old 09-03-2015, 02:03 PM   #14
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Could you attach a link to these Euro tires load pressure chart that your referencing., this is interesting stuff.
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Old 09-03-2015, 03:00 PM   #15
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I sure would, I told the previous owner and he was oblivious to the issue, and he used to run this thing loaded to the gills and I talked to a BerkXL owner recently and he said he never pays attention to tire pressure, weight, or his speed. I want to be as safe as possible. looks like its going to be 95/85psi for me

Some Credit Due to Phil for helping me and others with this. Thanks Phil!
Unfortunately, that's the way the majority of RV owners think. Just load it up and as long as it doesn't collapse in the middle, it's good to go.

Sheeesh!!!

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Old 09-03-2015, 03:16 PM   #16
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Kohersh - Your front axle (air bags and axle) is rated at 10,400 lbs. Your Michelin XRV255/80R22.5 tires are rated at 5,205 lbs each at the max. pressure of 110 lbs. When you put cargo in your weights only go up.

I tried to warn several about the Berk 340. I have it and know what it is about. Some posts advised to even upping the pressure. For one thing at 110 psi, it is hard riding and it is difficult to inflate to higher pressures.

The problem is not because of Freightliner, but FR. I had an upgrade to Michelin XZE2275/80R tires plus an air bag upgrade. I now travel loaded with around 18,100 lbs rear at 84 psi and over 11,000 front with 99 psi. The ride is much better.

Although FR rates the rear axle at 17,500, I researched it with Freightliner and believe it to be 19,000. So you say why do they lower the rating. I feel to allow the 360hp to have room to justify its price. Also, even if 19,000 is right, the Allison 2500MH tranny limits you to 33,000lbs total. Kohersh, you only have 220 lbs to that limit. You cannot pull a tank with the 340.
Hank
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Old 09-03-2015, 03:18 PM   #17
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I FORGOT THE TIRE CHARTS:

Tire Selector | Michelin RV Tires

Tire Selector | Michelin RV Tires
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Old 09-03-2015, 03:54 PM   #18
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Although FR rates the rear axle at 17,500, I researched it with Freightliner and believe it to be 19,000. So you say why do they lower the rating. I feel to allow the 360hp to have room to justify its price. Also, even if 19,000 is right, the Allison 2500MH tranny limits you to 33,000lbs total. Kohersh, you only have 220 lbs to that limit. You cannot pull a tank with the 340.
Hank
I agree it's a marketing ploy by FR. The actual RA capacity is at least the figure you mention and possibly even higher. An ex-trucker buddy of mine (drove for 42 yrs) and very familiar with FL says that the axle is most likely good to 20K lbs.

Hank, weren't you the guy that compared the BOM's for the front axle assembly on a 360 versus 340 and found the BOM's to be identical?

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Old 09-03-2015, 04:03 PM   #19
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Boo, you have a good memory for an old fart!
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Old 09-03-2015, 04:33 PM   #20
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You got me! I have to ask what is BOM stand for ?
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