Lighten 2009 F250 to increase 5th wheel kingpin margin

My 2005 F250 PSD was about 4500 lbs actual on the front axle. It had 5600 lb rated springs on the 7250 lb rated Dana 60 steer axle.

sail2liv wrote:
Sounds like your front axle may be over axle rating.....at 4900-course once you add some weight to the rear that may change.....what TP is suppose to be in the front tires? What are axle wt ratings? how long is wheel base....lots of stuff to look at to determine things....you never really know what it all will be unless trailer hooked up and weight determines as by guidelines for ccat scales.....good luck......I find more pin wt is better than less as long as not overloaded....

Unlikely. THe front axle weight rating on the 3/4 tons with the diesel is usually around 6K. (Same for the gassers with the plow prep package)

In my case (more or less the same truck with a V-10 instead of a diesel), front is rated for 6000 lbs, rear is rated for 6600, GVWR is only 9900lbs. Payload for mine is (IIRC) right around the 2600lb mark, and given the curb weights, I can essentially put that entire payload anywhere between the axles without exceeding my GAWR.

Diesels eat up a lot of available payload from a 3/4-ton, but the registration fees are significantly less than a 1-ton in many states.

Since that post, I sold the F250 and now have a 5500 with plans to upgrade to a 6000 lb truck camper in the future. StableLoads will engage your upper and lower overload springs sooner and you will get maximum use of your stock springs with less sag. I was able to carry to 4000 lbs on the rear axle with just the StableLoad upper pads and lower wedges. I also tow a 6000-8000 lb enclosed trailer and used Firestone airbags to to compensate for hitch weight that was on an extension and WDH. My rear axle weight was 7000 lbs with the camper and 8000 lbs with the trailer and camper. I ran 4500 lb Vision rims on all four corners with LRH 245/70R19.5 tires rated at 4805 lbs each. The rims were about the same weight as OEM, but the tires were heavier. I replaced the OEM shocks with adjustable Rancho shocks to handle this additional unsprung weight.

The upgrades did not turn my F250 into a F550 or even a F350 DRW, but it did turn it into something better than a SRW F350. It was a very comfortable setup and only swapped out due to my future desire to go bigger and heavier.

Bedlam wrote:
Your front axle is rated for 7250 lbs and the rear for 9750 lbs. The wheels and suspension are what keep your ratings down. Hop over the TC forum to see that 3/4t trucks are reliably hauling 4000 lbs of payload and can be capable of more.

Suspension can be modified so the overloads engage sooner or supplemented with additional metal or air springs, shocks can be replaced with heavier dampened models and side roll can be abated with active suspension components or sway bars.

Wheels can be upgraded to handle more than your axle rating without going to duals as long as you remember that rims and tires each have their maximum capacity.

Look at my profile details to answer many of your questions.

Thank you, you're so right. On an F250 with airbags the weak link is the tires. Mine are rated for 3,640 each, that's 7,250 total. Weigh the rear and and subtract. If you need more, put on 19.5" 5,000lb tires. My only enemy is the GVWR sticker of 10,000lbs.

If I was in your shoes i would hitch it up and load it ready to camp if it seems too saggy I would get air bags and perhaps at the same time some good shock absorbers.

Then I would take it to a scale and if the trucks rear axle is over or at the limit of the rear tire weight rating I would then find out what tires/wheels I would need to get a comfortable margin on the rear tires. On an 18 inch rim you should be able to get tires in the 3640 to maybe 3900 weight range 20s will be about the same and 19.5s can get way up there. Also make sure the wheels can take the weight too.

Then I would go camping. I am not telling you what to do, just saying what I would do.

The factory load calculations are based on the configuration of the truck when it left the factory. The number to focus on is the GCWR which is the total weight of the truck with its passengers and the total weight of the trailer with its contents combined.

It is that combined weight that the engine, drivetrain, brakes, frame, and suspension are engineered to handle. Exceeding that weight is what is going to cause premature wear and failure and possibly decrease safety.

The rear axles and wheel bearings on all heavy duty trucks will support a minimum of 8900 lbs. so take the scale weight of the truck and subtract that and you will know what the maximum load capacity is for the truck at the rear.

Next look at the tires and what their maximum load rating shows on the sidewalls. If it is 3200 lbs then the maximum at the rear axle is 6400 lbs and not the 8900 for the axle and wheel bearings. The weakest link is always the tires which is why dually trucks with 4 tires are the common solution.

There are tires from Nitto and Toyo for 17 and 18 inch rims that have a load capacity of 3750 or 7500 lbs for the pair at the rear. That should be enough for your planned king pin load. If not you can go to 19.5 rims and tires and get up to 8800 lbs. of load capacity at the rear axle.

Easy to verify this information. Just for grins go to a truck dealer's lot and look inside the gloveboxes of the F-250 and F-350 trucks and see how much the payload capacity varies depending upon the rims and tires put on at the factory.

More than three quarters of the trucks I see pulling 5th wheel travel trailers down the highway are doing so with SRW trucks. I have yet to see one that has broken down on the highway.

Seriously, don't over-think things here...

You're far from overloading either axle or the tires where you are, even with an additional 300-500lbs in the truck.

rhagfo wrote:


Just load it and go,you have 1,000 to spare on your rear axle rating, surprised you need air bags.

I agree. Our pin weight is 1900~lbs, 150 lb hitch and 150~ lb tool chest. Sits the truck level and tows like a champ.

bleedwater wrote:
Thanks everyone. ...........

Entire Rig on CAT Scale:
front axel weighed 4840 Lbs and its GAWR is 6000 Lbs (looks ok)
rear axel weighed 5160 Lbs and its GAWR is 6100 Lbs (looks ok)
thus the truck GVW weighed 4840 + 5160 and (coincidence) was exactly at my GVWR of 10,000 Lbs
(I will tend to be over the truck GVWR by 300 to 500 Lbs on trips, so I will be aware and minimize weight in the truck to help stay light as possible. ......

trailer axels weighed 8900 Lbs and its spread across 2 axels and four tires (looks ok since GCWR of truck is 23500 and GWR for 5th wheel is 13615)


Truck alone on CAT Scale:
front axel weighed 4840 Lbs
rear axel weighed 3340 Lbs

thus my kingpin weight is 1820
my 5th wheel in total is 10720 as weighed on Cat Scale (axel+kingpin) and is ok since the 5th wheel is rated up to 13615

Summary - This is a 34ft 7" 5th Wheel and not too heavy as 5th wheels go.
.

Thanks for all the discussion and suggestions.

Just load it and go,you have 1,000 to spare on your rear axle rating, surprised you need air bags.

Thanks everyone. I got some AirLift Load Lifter 5000 Ultimate Air Bags installed and drove perhaps 50 miles with 5th wheel attached to the Cat Scales.

I was not fully loaded for a big trip, but
for the truck, Fuel was full, had my 5 wheel hitch, no driver or passenger
for the 5th wheel had 60 Lbs of propane, 100 Lbs of batteries (I carry two), a few tools, all water empty and holding tanks empty

Entire Rig on CAT Scale:
front axel weighed 4840 Lbs and its GAWR is 6000 Lbs (looks ok)
rear axel weighed 5160 Lbs and its GAWR is 6100 Lbs (looks ok)
thus the truck GVW weighed 4840 + 5160 and (coincidence) was exactly at my GVWR of 10,000 Lbs
(I will tend to be over the truck GVWR by 300 to 500 Lbs on trips, so I will be aware and minimize weight in the truck to help stay light as possible. The tips on propane are good, I can use a single battery etc, but will be thinking lighter in front end of 5th wheel as we pack.
trailer axels weighed 8900 Lbs and its spread across 2 axels and four tires (looks ok since GCWR of truck is 23500 and GWR for 5th wheel is 13615)


Truck alone on CAT Scale:
front axel weighed 4840 Lbs
rear axel weighed 3340 Lbs

thus my kingpin weight is 1820
my 5th wheel in total is 10720 as weighed on Cat Scale (axel+kingpin) and is ok since the 5th wheel is rated up to 13615

Summary - This is a 34ft 7" 5th Wheel and not too heavy as 5th wheels go.
If you pull something like this with a highly optioned 4 wheel drive 3/4 ton truck, go to the scales so you never to exceed the rear axel weight rating. Do not haul much except humans, fuel, hitch and kingpin in your truck. Avoid carrying things you do not need. Carry stuff behind or closer to the wheels of the trailer as opposed to under the bed, cargo bays or in the bedroom closet - distribute your weight thoughtfully. Consider adding extra springs or air bags to help level the truck ride.

Thanks for all the discussion and suggestions.