Fifth Wheel Position

Keep in mind that you must make sure the trailer must clear the back of the cab and any accessories, this includes any freight over hang on the trailer. The truck frame must clear any thing under the trailer , landing gear or other things.

With this in mind, a good starting point is the center of the 5th wheel (this is the point where your king pin is locked in place) be placed just a hair forward of the center of your drive tandems.

Then weigh your truck and trailer under different loads for exact 5th wheel placement.

 

Back, flatbed you get long items, overhanging off the front a few feet helps

 

Most 5th wheel positions, even fixed ones, seem to have the king pin centered between the 2 drive axles.

 

Where ever you choose or get advice make sure air lines are not touching cat walk , just recently saw 2 guys got cut airlines while backing.... They reduced the gap and never paid attention to lines.

 

I seem to remember, air lines or light cord can't touch the deck plate.

 

I've run flatbed/ open deck for a number of years and have found that the best place for the 5th wheel is with the pivot centered between the drives. I don't normally do front overhang, though. Different trailers will give you different kingpin settings. With a skateboard I have just enough clearance between the corner of the trailer and my headache box. With an RGN I have a lot more space. Stepdeck is somewhere in between the two.

I've only ever moved my 5th wheel one time (company truck at that time) and didn't have good results. In fact, it took both of the mudflaps off.

 

It could depend on if it’s a spread axle or a close tandem slide also ,and how you load!

 

I slide as needed. Be sure to put a stopper bolt or atleast a paint mark at your farthest forward safe notch for a full jackknife.

My loads [decorative stone] are always heavy and my deliveries often exceptionally tight residential spots. Sliding will let you shorten up for tight work or lengthen out to get the steer legalish.

 

For best ride and less stress on equipment, centre of the suspension frame support points.
Easy if you only have 2, but most air ride trucks have 4, if you're smart you'll figure it out.
During winter you might want to move ahead a notch, maybe 2 if they're close spaced, you'll know the first time you go around a corner on a sheet of ice.
If you run 80k all the time, (34 34 12), set it so your steering axle is at 12k so you have a little more room if you have to move weight off the drives or winter driving in fun places.
Mind you, I guess a lot of trucks these days are 12k or heavier on the steering when bobtailing, so much for that theory.