Fifth wheel placement on a long WB tractor

This question is probably easily answered by some, so here I am asking.

Up here in the north (Canada), you don’t see many stretched tractors unless they are tri drive or tandem with an air lift. I’ve pulled lowboy/float with a 4 axle (tandem with air lift) before and never had issues. Here’s where my stupid truck comes in. It’s a 275” WB W900L. 16k front, 46k rears. It’s been stretched because come winter time, I pin up to a quick swap (think heavy wrecker business end). Now I know a long nose is hard to get weight up to the front and even harder with it being stretched.

Here comes my question..

How far forward (over Center of the drive axles) is it advisable to slide the 5th wheel? Because I use a quickswap, I’ve got enough slide rail to put it in the bunk if I wanted to. I just got the truck a few months ago and while I don’t haul gross weight every day, making it to a scale with a heavy load is few and far between.

I have an overweight permit for non divisible loads which allows me to put 14.6k lbs on the steer (smaller tires up front so I can steer in the winter and not float around) and 46k on the drives. The wagon I’m allowed roughly 67,000 k on the tridem.

I tare out at 12.7 steer, 24k drives and 17.2 on the tridem out back.

Typically with a 40-50k lbs payload shoved to the back my steer weight will only change 40-50 lbs. I’ve never been over on the drives and with that little payload I wasn’t concerned about the wagon.

Fast forward to the last few weeks where I’ve been in the Bush hauling heavy and I’ve noticed that my drives are a bit heavy and my steering is a bit lighter. Now fast forward to today and I had a 74,000 lbs nodwell to bring back into town. I finally was able to get to a scale and my steer was 12.5 k lbs, drives were 46,860 k lbs (front drive was a touch heavier than the rear drive, which put me over my 46k allowable and I was slightly under on the rear drive) and my tridem was bang on at 66 k lbs and change.

Tonight when I unloaded and did all my post trip, I slid the fifth wheel a few notches forward but as I said before, how far more forward past the Center of the drives is too far? I jackknifed to make sure I had all the clearance and I’m still ok.

I know this sounds pretty simple and it should be but maybe I’m just over looking things. 99% of the time, on any tandem I’ve ever pulled the 5th wheel is #### near bang on between the drives. Just don’t want to be way over on my front drive and not heavy enough on the rear.

Come winter time, having that extra steer weight will be nice regardless.

Thanks in advance fellas.

 

I forgot to ad something!

I’ve got a two pin placement for king pin on that wagon also. I’ve never measured the current hole but let’s assume it’s around 30-36”. The first hole looks to be about 12.

 

I was thinking of doing the load reversal but when I was looking at the machine, it’s pretty evenly balanced from what I could tell but it would be worth trying.

I had it shoved to as far back as I could put it to get those weights. I think I slid it forward 3-4 slots. I’ll have to count tomorrow.

 

Said boat anchor from scale ticket today.

 

I’m good for 46k on non divisible loads such as this one. We have 8 axle set ups however I was the dude with the load at the time. For future, we now know that those are too heavy for me but I’d like to get the steer axle a little heavier without causing too many headaches(drivability) on my drives.