Levelling 5th wheel for hitching and towing.

[Gene50]

What are the limits of acceptability for trailer levelling when hitched and towing?

The combination of the truck and trailer in my signature results in a hitching/towing situation where the trailer slopes almost 8 inches from pin to back bumper. 

The 5th wheel hitch in the box is in the lowest position and moving the pin box results in potential pin box mount interference with the box rails.

The rear bumper does have 15 inches vertical clearance on level ground which gives me about 1? of clearance when backing into my driveway. My driveway is fairly level so I'm a bit apprehensive about loading ramps onto some ferries. 

In addition, there is abnormal wear on one Tire on the rear axle which I Suspect has been caused in whole or in part by the unlevel hitch/towing.  This wear happened over the last 2000 miles as all the tires had good wear patterns when I first brought the trailer home. 

The Tire wear is a separate issue which I will deal with after the proper hitched/towing attitude is determined and obtained. 

Thanks for your consideration. 

 

[Rene T]

You have to have at least 5" clearance between the bottom of the RV and the truck bed rails. 6" is better.  If you can't lower the hitch and still maintain those numbers There are a couple of things you can do.
1st. You can flip the axles. In other words put the springs on top of the axles thereby raising the RV.
2nd. You can increase the size of the tires. Things to watch out for is make sure the tires don't rub on each other and that there is enough clearance between the top of the tires and the top of the fender well.

As far as one tire wearing you may need to have the axles aligned. They go in and actually bend the axles to achieve proper alignment. Sounds like either you have a bent axle or a spindle is bent.

 

[steveblonde]

the pin box on the 5er can also be adjusted - its more work  but doable

 

[Gary RV_Wizard]

Since the attitude is nose-up, you need to bring the hitch down (subject to the constraint Rene cited) or the trailer axles up. Or some of each.  But you already knew that...

The main effects of a nose-up attitude is excessive wear on the tires on the rearmost axle (both tires, not just one) and the tendency of the trailer to lift the rear of the truck in hard stops.  Whether the lifting occurs to any significant degree depends on how several forces come together, so may or not be a concern. If you can't feel any lift on the truck suspension in a hard stop from speed, it's probably not worth losing sleep over it.

I don't think there is any degree of tilt that is the divider between ok and too much. It just gets progressively worse as the angle increases.

 

[grashley]

In addition to the great advise above, if the hitch can not be lowered and the axles sit under the springs, the next step would be to add steel blocks to the frame at the spring attachment points to further lower the axles.  As Gary said, it may not be worth that effort.

 

[MtnGoat]

FWIW I had to lift the trailer axles 2" and drop the truck rear axle 2" to gain a trailer level attitude. The good part is there is plenty of ground clearance on the trailer now. Changing the pin box height will also change the gap between the pickup bed and front of the trailer.