New trailer spread spec

I believe you said 51' just sounds right, but wouldn't a 48' with set back spread be legal everywhere? That's what I like, but I'd want it built with only an 8' upper so it could still have container locks..

 

Fixed spread with a lift is a lot different than a fixed spread without a lift/dump. I suppose you didn't mean the latter...

 

Rear dump with a forward set spread is going to give you a whole lot of overhang, might not be legal if you are running it that way empty instead of just using it for turns, and is going to put a whole lot of weight on it when loaded.

 

I think you will have problems keeping under 40k on the spread with that much overhang. My opinion get a 48' with 9' top to have a 39' bottom with the spread set at the rear and you are legally allowed 4' of overhang without needing a permit in all states, so technically you will have 43' of usable space on the bottom deck. Get a shallow kingpin around 15" and you will be able to run your 5th wheel in the center of your 2 drives which is sufficient. Also if I am not mistaken you are legally allowed 3' of overhang off the front of the trailer, so you have 12' of usable load length space on the upper deck.
Also the 51' will be heavier in weight. Not that its just 3' longer, but with the tandem set farther forward the main beams that taper back to the front axle suspension will be shorter in length which means it will be heavier with the longer amount of shorter main beam height for the overhang of the 51'
Me personally I don't like spread axles, but I don't like sliding rear axles either. I would consider either an 8' 1" spread or a sliding closed tandem. Now since you absolutely rule out a sliding axle then looking at the 8' 1" spread gives you legally 38,000# instead of 40,000#. With the front axle 2' more to the rear will throw weight to the truck more and not that having 6,000# of comfort room to scale your load out with a 10 1" spread is too much I personally feel that 4,000# of comfort room would be sufficient in my opinion especially with a good set of on-board scales. I say comfort room because you are allowed 12k on steer, 34k on drives, & 38k on 8' 1" spread that is 84k gross.

KL

 

Most states will let you run more than 12 on the steer. On the overhang thing it varies by state, some you can’t exceed 53’ no matter where the overhang is.

 

And some states you can't have more than 48' without a permit on a 48 or shorter trailer. 48' trailer= zero overhang without permit.

 

That step deck will be worthless with the axles set forward like that. You will overload the spread very easily if you try and load any weight on the bottom deck.

 

Don't you just love when someone makes a blanket statement like every state allows four feet of overhang before requiring a permit?