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Open Roads Forum  >  Truck Campers

 > Dually Tire Air Pressure? Best Setting when camper is ON?

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Posted: 08/22/06 04:00pm Link  |  Print  |  Notify Moderator

Just purchased 6 NEW Michelin LTX M/S Tires (LT235 /85R16 120/116R
80PSI) Load Range E
I am getting conflicting input as to how much air I need to have in the tires when my BIG Fat Bigfoot is loaded on my truck... Door says 65 front and 60 rear....Tire dealer says 70PSI all the way around etc... Would love input from you all since many of you actually drive dually's with heavy campers for extended periods of time...
Tks, CWT

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western nevada

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Posted: 08/22/06 04:51pm Link  |  Print  |  Notify Moderator

70-75 front
80 rear duals with camper

65 front
45-50 rear without camper

'05 Dodge Cummins 4x4 dually 3500 white quadcab auto long bed.


Fairfield, CA, USA

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Posted: 08/22/06 04:52pm Link  |  Print  |  Notify Moderator

I'll get the ball rolling. I'd go with the tire manufacturer. I keep 75 psi all the way around; however, I do sense some roughness in the ride especially over the seams on concrete roadways. I may lower them to 70 and see what that does. I've only got 18K miles on them, so I don't know much about the wear factor yet... There was a good response on a previous thread (same or similar question). The jist of it was that you air your tires (cold) to a certain pressure, drive them for a specified time, and check the pressure again (hot). If the difference was more than a certain amount, you increased the pressure (cold) a specified amount and repeated the exercise until you got a "limiting" result. I can't remember the specified driving time or the acceptable pressure change limit, but it sounded reasonable to me, and I've lost the thread.

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round mtn

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Posted: 08/22/06 05:25pm Link  |  Print  |  Notify Moderator

Will the (LT235 /85R16 120/116R 80PSI) rub together? I have LT215/85R16E
and was told the 235 would rub. Alittle off topic but thought this might fit in. Thanks Cliff



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Posted: 08/22/06 05:45pm Link  |  Print  |  Notify Moderator


I had those as OEM, but mine were 215's. Not knowing any better at that time, I would always run 80psi for max load capability. I run XPS's now at 70psi. With 4 tires on the rear, you won't be near that max loading. I find 80psi very harsh, even with the camper loaded.

There's a good chance I'll be going back to the LTX's for my next set.

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Salem and Lakeview Oregon

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Posted: 08/22/06 06:01pm Link  |  Print  |  Notify Moderator

Here is my trick, maybe off topic but it seems to work for me.

I loaded the camper up ready to go camping then air the tires up to 80 and I drove out of my dry gravel driveway and onto the paved street. went around the corner where I could park and I looked at the tires to see if the dirt from the gravel has come off of the tire tread face. I did this until the tires show no dirt across the face of the tread. This is a good way to get close. Check your tires for temp and tread wear and adjust tire pressure accordingly.

At 80 PSI my tires are running on the centers and there is about 1" of dirt on the tire tread edge. I back down the PSI until there is no dirt on the edge and you should be close to running the PSI that works for that load. Mine is running 65 rear and 70 front with the camper loaded.

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SouthWestern ,Oklahoma

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Posted: 08/22/06 08:49pm Link  |  Print  |  Notify Moderator

I ran 72 rear and 65 front on our first road trip to Colorado with speeds up to 80mph. The truck was solid and ride was smooth & stress free,this with factory tires.

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Boise, Idaho

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Posted: 08/22/06 09:01pm Link  |  Print  |  Notify Moderator

I go by the door sticker empty......65 front and 40 rear
I go by the tire sidewall loaded....80 all the way around.

An underinflated tire causes heat and heat is a tire's worst enemy.

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The Mad Norsky

Yankton, South Dakota

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Posted: 08/22/06 09:02pm Link  |  Print  |  Notify Moderator

I will not take credit for this. A forum member named Camp, Forrest, Camp! came up with this. It looks good, have not tried myself, but it surely is at least a guideline to go by.

Follows is a copy of a post made by the above noted member of the forum:

Do I have to change the inflation pressure when carrying the camper?
-- Yes, unless you want to keep them at the high pressure and have a really crummy ride when empty.

To what?
-- Some people say that you should max out. In a camper like yours, that's a reasonable conclusion. In my opinion, the air pressure should match the load. Load up your camper and weigh your truck as outlined below. Make sure you have seperate weights for the front and rear axles. At this point, apply the following formula based on information stamped on the tire and you weights:

1) (max rated payload)*(number of tires per axle) = (max axle payload)
2) (max axle payload)/(max psi per tire) = (pounds per psi)
3) (axle weight)/(pounds per psi) = (inflation pressure)

Front axle:
1) (2293lbs)*2 = 3586lbs.
2) (4586lbs)/80psi = 57.325 lbs/psi (round to 57)
3) (4000)/57 = 71.175psi (round to 71)
Rear axle:
1) (2093lbs)*2 = 3586lbs.
2) (8372lbs)/80psi = 104.65 lbs/psi (round to 105)
3) (7200)/105 = 68.571psi (round to 69)

Never exceed the tire's rating, they're most susceptible part of your chassis and it's freaky when they blow. Don't worry, you won't automatically fly off the road, just remain calm. These number are related to TIRES ONLY, they do not apply to the truck's Gross Axle Weight Rating (GAWR) defined by the manufacturer. These numbers apply to tires based on the temperature indicated on the side wall. If it says "cold", then inflate them when cold and likewise if they are rated for warm. Tires are often rated for a lower may number when used in a dually configuration.


Central MA

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Posted: 08/23/06 07:59am Link  |  Print  |  Notify Moderator

As already mentioned, you've got four tires in the back so you don't need max pressure. I have a similar setup to Joec and also run 70 in the front and 65 in the rear duals. I didn't do the scientific dust test (which is a good idea BTW) but I found through trial and error that it works well for me. The camper is about 4000lbs.

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