2018 1 Ton Dually Suspension Pulling 5th Wheel RV

[TowPro]

I just looked at the weight slip on my 18 dually 2wd 3580 rear with wife and I, plus full fuel. 4wd is around 400 more but most of that is on front

 

[Cummins12V98]

You read the chart wrong. That is for single use. For dual tires 45 lbs inflation is 7480 capacity. Snoking

Crap! Yer right, ok run 50psi

 

[dfb]

I drive from WA thru the Bay Area, and then on to FL at least once a year, with my 5th wheel. The area you are writing about is one of the worst sections of road in the US. Another really bad area is I-10 near the LA-TX border. I am constantly looking in my rear mirrors to see if the tires and axles are still on the rig, when going thru those areas. Sounds like you have a good setup, so I wouldn't change anything (maybe air pressure), but try to slow down. Often there is just no way to avoid those bad areas, so the only thing you can do is slow down and try to avoid the bigger pot holes.

The 10 going to Lousianna is the WORST. WE LOST our slide trim and blinds..they came off the walls. Another cruudy one is the 40 going into Oklahoma city! What are they doing with all that gas tax money? Are they stealing it from the motorists for other things?.

 

[2Evil4U]

I drive from WA thru the Bay Area, and then on to FL at least once a year, with my 5th wheel. The area you are writing about is one of the worst sections of road in the US. Another really bad area is I-10 near the LA-TX border. I am constantly looking in my rear mirrors to see if the tires and axles are still on the rig, when going thru those areas. Sounds like you have a good setup, so I wouldn't change anything (maybe air pressure), but try to slow down. Often there is just no way to avoid those bad areas, so the only thing you can do is slow down and try to avoid the bigger pot holes.

I will not tow I10 between Vidor and Baton Rouge. I take TX 12 out of Vidor to LA190. It adds about 30 minutes but I don't worry about ripping an axle off the trailer.

 

[Rob_Fla]

OP has the close system OEM factory rear air suspension, not air bags.

"Not Air Bags"
We have the OEM Factory Rear "Air Assist" on our 2018 RAM and love it towing our 5th Wheel, looking at the rear suspension, sure looks like "Air Bags" to me.
We tow with 70 psi in front tires and 65 psi in the rear tires and Suspension Mode set to "Alternate Height" mode (which makes our truck ride very level front to rear), ride is much better than our previous GM 3500HD.

 

[SnoKing]

"Not Air Bags"
We have the OEM Factory Rear "Air Assist" on our 2018 RAM and love it towing our 5th Wheel, looking at the rear suspension, sure looks like "Air Bags" to me.
We tow with 70 psi in front tires and 65 psi in the rear tires and Suspension Mode set to "Alternate Height" mode (which makes our truck ride very level front to rear), ride is much better than our previous GM 3500HD.

Cummins12V98, who has had two 4th gen duallies recommends 80 PSI in the fronts all the time. 70 is only good for 5630 on the front axle. You are most likely very close to that on the front axle.

And he also advises to set 1/64-1/32" toe-in verses the factory's 1/4" for even tire wear.

 

[Cummins12V98]

Even the door jamb has 80psi for the fronts. For the best tire wear 80 is correct along with a PROPER 1/64 toe setting. Do so and you will thank me.

 

[dfb]

The rear is an 'AUTO LEVEL"...instead of 8 or 10 leaf springs, the truck uses air to keep the rear from sagging. It is not an 'air ride'. On our 2004 dually, this Montana pin weight pushed the trucks rear onto the "helper springs or overload springs' . The level system now keeps the truck from riding low in the back..
As far as getting banged around!... its our 3rd world country roads..

 

[6V92TA]

Even the door jamb has 80psi for the fronts. For the best tire wear 80 is correct along with a PROPER 1/64 toe setting. Do so and you will thank me.

I run 80 in the front but I've never had an alignment no have tire wear problems... should I still thank you or just thank myself for being so lucky ?

 

[Cummins12V98]

I run 80 in the front but I've never had an alignment no have tire wear problems... should I still thank you or just thank myself for being so lucky ?

Do you keep the fronts on the front??? If not you may not notice.

YES, you should ALWAYS thank me.

 

[Cummins12V98]

"It is not an 'air ride'"

Depends on how you look at it. Remove the bags and the axle will hit the bump stops. YES the BAGS are what holds up the truck.

 

[Cliffman]

Here is a tire pressure chart. Based on your actual load I would run 45 rears. That will give you 8,220# capacity.

View attachment 107457

Where did you get this chart? I'd love to run 45 in the rear but that low kinda scares me!

 

[SnoKing]

Where did you get this chart? I'd love to run 45 in the rear but that low kinda scares me!

Air inflation tables are universal across tire manufactures. Any chart from any tire manufacture we list the same inflation for a LT235/80R70E tire. Ron looked at the chart wrong for duales, as I noted earlier. 45 lbs is good for 1870 per tire, 7480 for 4 tires. 35 lbs is good for 1570 per tire or 6280 for 4 tires.

Here is Firestone's LT235/80/70E is near the bottom.

https://commercial.firestone.com/co...015/FS_TBR_load-inflation-tables_web_2014.pdf