Formula for Determining Needed Clearance for Fifth Wheel 90 Degree Turn

Updated 07/25/2020 | Published 02/14/2016

Question:

Okay, I am pretty sure I saw a formula that can be used while researching what type of hitch I need to use dependent on the size, etc of my truck for towing my fifth wheel. I cant find d it now. Help.

asked by: Patti

Expert Reply:

Sounds like you are looking for the formula for determining if you have enough clearance to make 90 degree turns with a fifth wheel trailer hitched up to a truck.

The formula you are referring to is this:

(A + B) - C = Clearance
A = Distance from the fifth wheel jaw center to the truck cab
B = Offset used (slider clearance or Sidewinder offset)
C = Width of the nose of the trailer divided by 2.

I attached a couple help articles for you to check out on fifth wheel towing as well.

expert reply by: Jameson C

Brad B.

7/19/2020

I am curious how the formula can address if the hitch point is in front of the 5th wheel nose. I’m in the process of trying to determine a new hitch for my 2500 Ram short bed. Traded off my 2500 Chevy and I want a new hitch to utilize the puck system in the new truck. But the ram bed I didn’t realize was 2” shorter than the Chevy. At the house I do need to do a 90 turn and unfortunately my 5th wheel is not a rounded nose, but the kingpin is in front of the nose. Any assistance would be greatly appreciated as I prepare to make my purchase.

Chris R.

7/23/2020

How far in front of the nose does the king pin extend? I suppose you could essentially add this distance to the "offset used" number in the formula.

Brad B.

7/25/2020

@ChrisR my kingpin appears to be approximately 6” in front of my furthest point sticking out from my nose. So based on rough measurements I should be 38” from cab to Axle. Then if I purchased the B&W Companion slider that is 12” right ? So my formula would be as such (38+12+6) - 48 = 8 making sure having my kingpin in front does in fact increase my clearance as I believe you suggested. Thanks so much for your help!