Maximum legal weight for 40ft 48'' spread axle?

Discussion in 'Expediter and Hot Shot Trucking Forum' started by me only, Dec 1, 2011.

  1. me only

    me only Medium Load Member

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    My truck weighs 7700lbs ,Trailer weighs 7000lbs .What's the most weight you put on your 40ft 48'' spread axle and stay legal?.I haul light stuff now around here .
     
  2. Pedigreed Bulldog

    Pedigreed Bulldog Road Train Member

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    What is the distance between the front drive axle and the rear trailer axle? With my truck and a 39' frameless end dump, that measurement is right at 36'....so if you're pulling a 40' trailer, I would GUESS you'd have 4 axles in roughly 37'...which lets you carry 66,500 on those 4 axles...although there is an exception in the bridge formula which allows two consecutive sets of tandem axles to carry 34,000 pounds each if the overall distance between the first and last axles of the tandems is 36 feet or more.

    I'm not entirely sure a spread axle would be considered a "tandem" as it is generally viewed as being two single axles, so it MAY not fall under this exception....in which case, you'd be better off with a tandem axle trailer instead of a spread...because then it WOULD fall into the exception which allows 68,000 on the drives + trailer instead of only 66,500 on those same 4 axles.

    That covers the "trailer bridge". Now you need to look at the "tractor bridge". What is the distance between the center of the steer axle to the center of the rear drive axle? If the axle, suspension, and tires are all rated heavy enough, you could possibly run 13,500 on your steers to make up for the 1500 pounds you lose on the trailer bridge.

    Then measure from the center of the steer axle to the center of the rear trailer axle to get your overall bridge. As long as that distance is at least 51', you can go to 80,000 provided the tractor (steer + drives) and trailer (drives + trailer) axle groups are all within their allowed weights.

    13.5/34/32.5 would be legal if you have at least 16 feet on the tractor bridge and 51' between the center of the steer axle and the center of the rear trailer axle.

    13.5/32.5/34 would be legal if you have at least 14 feet on the tractor bridge and 51' on the overall (5-axle) bridge.

    Or, if you want to have a balanced load between drives & trailer axles, 13.5/33.25/33.25 would work too...and then you only need 15' on the tractor bridge and 51' overall.

    Of course if you're running on a 12K steer axle with LP22.5 LRG tires, you can't legally carry 13.5K on your steers.

    Basically, get out a tape measure and consult the bridge formula & manufacturer's ratings for your truck.

    http://ops.fhwa.dot.gov/freight/publications/brdg_frm_wghts/bridge_formula_all.pdf


    So now to answer your question: What's the most weight you put on your 40ft 48'' spread axle and stay legal?

    1) Measure your truck to determine axle spacing.

    2) Consult the bridge formula to determine maximum allowable weights for the axle groups.

    3) Check your manufacturer's rating for the axles. If lower than the bridge formula would otherwise allow, the manufacturer's ratings are your limit.

    4) Subtract your tare weight from the limits imposed by the bridge law and your manufacturer's ratings. That is what you can legally load on your trailer IF it is loaded in a manner which distributes the weight to keep your axle groups within the bridge formula and the manufacturer's ratings.
     
  3. 07-379Pete

    07-379Pete <strong>Crusty Commando-Pete</strong>

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    A 7700 pound truck?? WTF My motor weights that much alone.:biggrin_2559:
     
    7122894003481 Thanks this.
  4. me only

    me only Medium Load Member

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    i hope so when i drove semi myself ,it was also heavier :biggrin_25516:

    im retired and want to do something .so im lightweight hotshot .have plenty of freight with out busting my fanny and home every night.do as i want with no comitiment to anyone .:biggrin_2559:
    im not doing this to make a living .its almost a hobby to me and good tax rite offs .i love to drive .
     
    Last edited: Dec 1, 2011
  5. SHO-TYME

    SHO-TYME Road Train Member

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    What are the axels on the trailer rated at? That's what you have to worry about, you can't go by the same formula as a semi.
     
  6. me only

    me only Medium Load Member

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    13000lb each dexter axels
    [​IMG]
    [​IMG]
     
  7. Pedigreed Bulldog

    Pedigreed Bulldog Road Train Member

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    That's not a spread axle. That's a tandem. If they are rated at 13,000 each, that's 26,000.

    Your steer axle has a maximum weight rating.

    Your drive axle has a maximum weight rating.

    Your trailer axles have a maximum weight rating. (26,000#)

    Your truck has a maximum tow capacity rating.

    The hitch has a maximum trailer weight rating. (typically 25,000 for a gooseneck, although I've seen them rated higher)

    Your truck and trailer are registered for a specified weight.





    You can legally haul as much as you can carry up to those limits.
     
  8. CondoCruiser

    CondoCruiser The Legend

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    Is it a Big Tex 40' gooseneck??

    If so, it's rated at 22,500.

    If you max out, load it so the weight is distributed between your drives and tandems.
     
  9. me only

    me only Medium Load Member

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    big tek 22gn 48'' spread axle 35+5 =40ft is how they list it
     
  10. Motownfire

    Motownfire Light Load Member

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    What weight are you apportioned for ???