Proper Fifth Wheel Hitch Height From Ground
It is required a minimum clearance of 6″ between the truck bed rails and the underside of the overhang (4) or gooseneck of the fifth-wheel RV (1)(2) (3). Whether the fifth wheel sits lower in height than the towing vehicle, it is expected to complete a height adjustment in the corresponding direction. For this adjustment to be performed, it is demanded to determine the proper fifth wheel hitch height from ground, among other relevant calculations thereof.
The proper fifth wheel hitch height from ground is 47″, with a tolerance range generally considered between 45″ and 49″ and requires a leveled fifth wheel. This fifth wheel height will depend also on how high or low the trailer is adjusted by its landing gear.
Furthermore, we encounter also in the industry a broader tolerance range located from a low of 38″ to a high of 52″. In the course of making decisions as to hitch selection and mounting method, setting the aforementioned average target of 47″ is not an unreasonable starting point.
You should also have at least 6″ clearance between the top of the bed and the underside of the trailer at the closest point, most surely the tailgate. A clearance of 8″ is needed if you go off-pavement, such as a rough pasture. If you cannot achieve this requirement, then you need to either lower the truck or raise the fifth wheel.
Many RV owners would not worry as much about the proper fifth wheel hitch height from ground, as they would worry about the actual overhang on the front of the fifth wheel. There is where it is required to have at least 6″ of clearance between the underside of the overhang and the bed rails on the truck.
The proper fifth wheel hitch height from ground is not the relevant variable to know, because it is needed to have 6″ or more clearance from the bed rails of the towing vehicle, and only when the latter is calculated you will adjust manually the height of the hitch or the pin box up or down until you are within the aforementioned minimum of 6″ clearance required.
I see lots of concerns about which is exactly the standard for the proper fifth wheel hitch height from ground and these concerns have themselves not much justification because I will manually adjust the hitch or the pin box up or down until I am within 6″ to 8″ specification range.
Therefore, the adjustable hitches or the pin boxes on the trailers can be raised or lowered to allow clearance.
The historical standard number is 46-47 inches and there was a time when many brands did list pin height on their brochures. There was also a lower standard of 41-42 inches for lite units designed for 1/2 ton and even mini trucks. These lite units typically had 13 inch wheels and rubber torsion axles.
I have the impression that manufacturers have an obligation to buyers to include this critical information in their documentation, in their product sheets. With today’s taller trucks, it would even be a sales plus to have a higher pin height and actually announce that fact publicly and advertise it thoroughly.
Next Step After Setting The Proper fifth wheel hitch height From Ground: Establish The Adequate Clearance Between The Truck Bed And The Fifth Wheel
After determining the proper fifth wheel hitch height from ground, we have to work on the question about having enough clearance between the truck bed and the fifth wheel. This clearance is 6″ at least and up to 9″.
The clearance between the truck bed and the fifth wheel is anywhere from 6″ to 9″ measured from the truck bed to the underside of the overhang of the fifth wheel.
If we measure the height of the sides of the truck bed at the highest point, which is usually the bed rails that we normally have sitting on top of the truck, and compare that to the underside of the overhang on the trailer, that should give us a good number and that is the measurement we have to do.
Sources And References
Karnopp, Dean (2004). Vehicle Stability. CRC Press. p. 93 and others. ISBN 9780203913567. Retrieved 2021-11-29.