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Front tire pressure for 3500 long bed pulling 5th wheel

smokeylew
Explorer
Explorer
Have a 2016 Ram diesel long bed and pull a 36' NuWa 5th wheel. Haven't had the 5th wheel that long. Prior to this I pulled a heavy TT with an Egualizer hitch. Always put max air pressure in all 4 TV tires for towing. Weight distribution on TV is much different with 5th wheel.

Door sticker on Ram states 60# for front and 80# on rear.. Can anyone with similar TV and 5th wheel combo advise what front tire pressure should be? I've been putting 74# in front tires while towing 5th just on gut feeling. Tires have max 80# on sidewall. Trailer is 12,300 unloaded. 15,500 max.

Thanks
29 REPLIES 29

wnjj
Explorer II
Explorer II
Grit dog wrote:
Durb wrote:
Let's see, 17 replies, 5 say go with the Ram engineers, the other 12 suggest tire pressures that differ from each other and the factory, sometimes quite a bit. What is the OP to do?


Realize that if you don't want to or can not discern/understand, the relationship between tire size/rating/pressure/load then use the "engineers" reccomendation. It's the "safe for max load" scenario.
All valid points, comment on the higher pressure, less traction/contact patch is also true, but with that realize what is "enough" vs what may be "better." You're not going to wear your tires out by tomorrow or skid to a fiery death with nominal over inflation, in the context we are discussing here. You WILL have an unnecessarily stiff ride and maybe get .1mpg better fuel economy.

Regarding engineers' design parameters, I'm a civil engineer but work on the construction side. One of the projects I'm looking after is a design build, and alMost DAILY I'm able to economize a preliminary design from our designer that may not take into account real world conditions or limitations. It's just different views or knowledge on the same subject, and just like auto mfgs design parameters, they are not able to take into account individual conditions/uses, so the design needs to be as absolutely conservative as practical to envelope the greatest majority of conditions/uses.
From there, if one understands what they're dealing with, modifications or improvements can be had.....for free. Because they were there already, hiding behind an ultra conservative design.


Excellent post!

Electronics engineer here and the same design parameter concept exists in my world .

You also have to consider that tire pressure, like many other things consists of trade-offs. In this case between load capacity, ride quality, braking contact patch, cornering ability, puncture resistance, tread wear and likely more I missed.

As you say, knowing what you're after and what you may need more of versus what you can spare factors in. Consider too that if braking is what you're after, loaded vehicles tend to add plenty of that load to the front when you are braking the most. Loads are not static,

RoyJ
Explorer
Explorer
Just to add to Grit dog's point - look into the owner's manual of German sport sedans, often you'll see multiple psi specs, one for each speed and payload bracket. Even in my subcompact Mini, the range goes from 35psi (low payload, under 120 km/h) to 50 psi (max payload, 220 km/h top speed).

That's an example of the OEM engineer trying to tailor a design spec to each end user application. In Germany, probably the most engineering oriented culture, it works.

In our sue happy North American culture where people never read a manual, and talk to their lawyer the minute their tire blows, OEMs are forced to take a different approach.

Grit_dog
Navigator
Navigator
Durb wrote:
Let's see, 17 replies, 5 say go with the Ram engineers, the other 12 suggest tire pressures that differ from each other and the factory, sometimes quite a bit. What is the OP to do?


Realize that if you don't want to or can not discern/understand, the relationship between tire size/rating/pressure/load then use the "engineers" reccomendation. It's the "safe for max load" scenario.
All valid points, comment on the higher pressure, less traction/contact patch is also true, but with that realize what is "enough" vs what may be "better." You're not going to wear your tires out by tomorrow or skid to a fiery death with nominal over inflation, in the context we are discussing here. You WILL have an unnecessarily stiff ride and maybe get .1mpg better fuel economy.

Regarding engineers' design parameters, I'm a civil engineer but work on the construction side. One of the projects I'm looking after is a design build, and alMost DAILY I'm able to economize a preliminary design from our designer that may not take into account real world conditions or limitations. It's just different views or knowledge on the same subject, and just like auto mfgs design parameters, they are not able to take into account individual conditions/uses, so the design needs to be as absolutely conservative as practical to envelope the greatest majority of conditions/uses.
From there, if one understands what they're dealing with, modifications or improvements can be had.....for free. Because they were there already, hiding behind an ultra conservative design.
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5โ€ turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold

Slowmover
Explorer
Explorer
Me Again wrote:
wnjj wrote:
kzspree320 wrote:
I'll stick with the door sticker recommendations for air pressure at axle weight ratings. For me that's 60 front and 80 rear. The fifth wheel adds no real weight to the front axle so I don't get the need to increase it so much.


Weight on the front is only part of it. Higher pressure up front may reduce some of the wiggle (sway). Tires see much more than just down force.


Over inflated tires have a smaller contact patch which reduces braking ability and they are more likely to receive impact damage! I noted 5 additional pounds of inflation for those concerned. 20 pound more = NO WAY.


Agreed.

Use a Scale to find the real Load. And stay inside vehicle manufacturer rating.

My towing combo is over 17k. And I still get over 100k on those too soft for some Michelins. Pressure according to Load. Test for pressure rise, and you're done.
1990 35' SILVER STREAK Sterling, 9k GVWR
2004 DODGE RAM 2WD 305/555 ISB, QC SRW LB NV-5600, 9k GVWR
Hensley Arrow; 11-cpm solo, 17-cpm towing fuel cost

Me_Again
Explorer II
Explorer II
wnjj wrote:
kzspree320 wrote:
I'll stick with the door sticker recommendations for air pressure at axle weight ratings. For me that's 60 front and 80 rear. The fifth wheel adds no real weight to the front axle so I don't get the need to increase it so much.


Weight on the front is only part of it. Higher pressure up front may reduce some of the wiggle (sway). Tires see much more than just down force.


Over inflated tires have a smaller contact patch which reduces braking ability and they are more likely to receive impact damage! I noted 5 additional pounds of inflation for those concerned. 20 pound more = NO WAY.
2021 F150 2.7 Ecoboost - Summer Home 2017 Bighorn 3575el. Can Am Spyder RT-L Chrome, Kawasaki KRX1000. Retired and enjoying it! RIP DW 07-05-2021

wnjj
Explorer II
Explorer II
kzspree320 wrote:
I'll stick with the door sticker recommendations for air pressure at axle weight ratings. For me that's 60 front and 80 rear. The fifth wheel adds no real weight to the front axle so I don't get the need to increase it so much.


Weight on the front is only part of it. Higher pressure up front may reduce some of the wiggle (sway). Tires see much more than just down force.

Me_Again
Explorer II
Explorer II
Grit dog wrote:
To Durb, those pressures on the door jamb are arbitrary......but generally safe, for those that don't know how to adjust for tire size, weight, conditions. That's why the newer 2500s all got 80 psi idiot lights in them when most people on mOst days (running empty) would be much better served with significantly lower tire pressure.

To everyone else, some good reccomendations, some not applicable, like those quoting pressures for a dually with pizza cutter tires when OP is asking about a srw truck with presumably different tires.
Tire size and capacity also play as large a role as actual applied weight.


YnotTurbo caused the confusion, as he has a dually when OP has a SRW. Chris
2021 F150 2.7 Ecoboost - Summer Home 2017 Bighorn 3575el. Can Am Spyder RT-L Chrome, Kawasaki KRX1000. Retired and enjoying it! RIP DW 07-05-2021

kzspree320
Explorer
Explorer
I'll stick with the door sticker recommendations for air pressure at axle weight ratings. For me that's 60 front and 80 rear. The fifth wheel adds no real weight to the front axle so I don't get the need to increase it so much.

garyp4951
Explorer III
Explorer III
70 to 80 in front, 80 rear towing on my 2500 4x4.

Cummins12V98
Explorer III
Explorer III
Know your loads and use the weight/inflation chart for your tires to determine proper psi.
2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's
37,800# GCVWR "Towing Beast"

"HeavyWeight" B&W RVK3600

2016 MobileSuites 39TKSB3 highly "Elited" In the stable

2007.5 Mobile Suites 36 SB3 29,000# Combined SOLD

Jim2007
Explorer
Explorer
Hi.. I have a 2016 Dodge 2500 long bed and tow a 5th wheel trailer. Max weight ready to camp is no more than 10k. So, I am towing less weight that you are. I use 70psi in the front tires and 80psi in the rear. Jim2007
TV: 2016 Dodge 2500 Diesel
Rig: 2013 Heartland, Sundance, 5th wheel

Durb
Explorer
Explorer
Let's see, 17 replies, 5 say go with the Ram engineers, the other 12 suggest tire pressures that differ from each other and the factory, sometimes quite a bit. What is the OP to do?

Grit_dog
Navigator
Navigator
To Durb, those pressures on the door jamb are arbitrary......but generally safe, for those that don't know how to adjust for tire size, weight, conditions. That's why the newer 2500s all got 80 psi idiot lights in them when most people on mOst days (running empty) would be much better served with significantly lower tire pressure.

To everyone else, some good reccomendations, some not applicable, like those quoting pressures for a dually with pizza cutter tires when OP is asking about a srw truck with presumably different tires.
Tire size and capacity also play as large a role as actual applied weight.
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5โ€ turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold

Cummins12V98
Explorer III
Explorer III
BobKrogstie wrote:
I run 73 front, 80 rear duals, scaled 23600 gross, 3320 pin weight.


Your front psi is correct for being 2wd but you are WAYYYYY over on the rears. With your load 55-60 would be plenty of air when loaded.
2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's
37,800# GCVWR "Towing Beast"

"HeavyWeight" B&W RVK3600

2016 MobileSuites 39TKSB3 highly "Elited" In the stable

2007.5 Mobile Suites 36 SB3 29,000# Combined SOLD