Weight Distribution across a flatbed trailer?

On a 48’ spread.

4 coils: 1 of each centered over the spread and 1 of each the same distance from the front edge of the deck. Or, 2-5K centered 16’ forward of center point and 2-10K centered 8’ rearward of center point.

3 coils: the 10K centered on the spread and the 2-5K centered on the same distance from the front edge of the deck.

If you have 3 coils of equal weight, you can put one 16’ forward of the center point and the other two centered 8’ behind the center point. Or, 20’ forward and 10’ rearward. Or, 12’ forward and 6’ rearward. The 2 rear coils should be 1/2 of the forward distance. Your rearward weight is double the forward weight, so you can only be rearward half the distance of the front weight. It’s why this setup, also works in your first scenario.

 

Reading your inputs have brought up some questions for me, too. I have a 53' spread fixed axle trailer, the 5th wheel is set to the most end position (almost centered between the drive axles). The empty weight of the combo is 31k. I had 47-48k max of lumber or wallboards and I weigh every time I get 44k+ to get understanding of my weight distribution. So my question is I had:
12k on steering
25k on drive
40-41k on trailer (until I figured out where to move this kind of loads).
I've never had over 28k on my drive axles. How do you get over 30k on the drive axles while staying in the 80k limit?

P.s To the topic and the center - I have a white lane on the trailer marked by the mfg which is offset to the back by many means.Yet whenever I haul 45-46k single coils I let them loaded in the center between the drive and the spread axles and it always weighed perfectly (like 12k, 28k, 36k). So it is really your actual setup depending.

 

Just a hint - I bought labels on Amazon and marked all the pockets. Once loaded, I take out my phone, write down the numbers and it makes so much easier. Also to count the length of needed. A $20 buy saves so much time. Especially if you do strapping from both sides (I do).

 

What are those numbered labels representative of, though? Length? Position?

For your question about 30k on drives, on a spread, that's going to be determined solely by the weight of the load, and where you put it on the trailer. More to the front, will put more on the drive, and to a certain extent, take it off of the drives...think teeter totter effect. Moving the 5th wheel more forward will put more back on the steers, should you be too light. I hope that's understandable and helpful.

 

The labels are just to make it easier for both strapping and positioning, too. Say I'm strapping in 3, 10, 20, 40 etc remember/write down the numbers and do this on the other side. Also, e.g for the length, I know where the center of the load should be and so it's easier to calculate the exact placement on the trailer. It's just quicker. Maybe it sounds too paranoic but I like when everything is as much precised as possible.

To the drive axles, I understand that it's depends on how close over them the load is. My point was I didn't understand why would someone put more weight on them instead of the trailer. Like I mentioned a good weight distribution at max is 12k(s), 28k(d), 40k(t) rather than loading, say, 12k+, 33k, 33k. This is to me and so I'm asking if you'd rather split it more evenly between the drive and trailer axles.

 

Well, besides scaling legally, the distribution is to improve the handling characteristics and the ride. Weight in the wrong place can make for a really bouncy ride or a dead hit on bumps that rattle your teeth. Distribution isn't JUST about scaling. Nothing like being on a bucking bronco for 1,000+ miles.

 

The more balanced the weights are between drives and trailer, the better the fuel economy will be and the easier time you will have in the hills.

I would also guess balanced weights would make backing a spread easier, but that's a guess.

 

It's a good guess. Glad you mentioned the fuel economy, too. Turning with a spread is hard enough depending on the angle, without adding excessive weight on the spread as well.

 

Thank you @gentleroger and @CAXPT I kind of missed that point. It's always painful to see the fron trailer axle at a turn not even talking about an u turn. I thought loading more on the drive axles would also proportionally increase the load on the steering. Which, I guess, isn't the case as long as the 5th wheel is far in the rear. I'll definitely try to make it closer to 12k, 30-32k, 34-36k next time.
P.s it's just sometimes a hard debate with the shipper who has been doing this kind of loads "all his life" and doesn't see the difference between a 48' and a 53'.

 

It will impact the steers, just not by much - 100 to 200 lbs max. Fuel level has more of an impact.