Suspension weight ratings

Discussion in 'Peterbilt Forum' started by Sandsailor, Mar 25, 2023.

  1. Sandsailor

    Sandsailor Bobtail Member

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    I don’t know if this is the correct place to ask this question, but I been searching online for the Peterbilt Flex Air weight rating.

    as far as I found somewhere it said that it came for 38k on the suspension(flex air) and the differential are Eaton 40k

    my truck has Flex Air, so I’m guessing my tandem weight limit is 38k?
    Or is there different ratings for Flex Air? I know someone who has grossed 105k, which would put his trailer and tractor tandem at ~46k.
     
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  3. Animosus

    Animosus Medium Load Member

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    AG-380 / Flex Air is a 38k suspension.
     
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  4. Cat sdp

    Cat sdp . .

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    Isn’t the rears stamped inside the door jam ?
     
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  5. Sandsailor

    Sandsailor Bobtail Member

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    the rears are rated for 40k, but the Flex Air suspension is supposed to be rated for 38k hence my question.

    https://www.pbtruck.com/Parts/Catalogs/Peterbilt-Suspensions.pdf

    if you look at this chart it shows Flex Air as 38k. Just wondering if there’s other ratings
     
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  6. Sandsailor

    Sandsailor Bobtail Member

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    I suck at seeing replies here. That’s what I was thinking but almost always there’s information I don’t know about and like to double check.
     
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  7. special-k

    special-k Road Train Member

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    Just go off the door sticker.
     
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  8. Sandsailor

    Sandsailor Bobtail Member

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    So I finally got around to checking my door sticker(I was in another).

    my door sticker says:

    gvmr: 50,000lbs
    Front axle: 12,000
    2nd axle: 19,000
    3rd axle: 19,000

    which would total at 38k for the Flex Air.

    but this confused me. My brother has the same truck but a 1999.

    This are his specs with a Low Air Leaf

    Gvmr: 48,000
    Front axle: 12,000
    2nd axle: 18,000
    3rd axle: 18,000
    And we always assumed his was a regular 40k tandem and he has permitted up to 46k on those and driven many miles, I asked him if the DOT had checked that before, he said, they just look at the permits and send me on my way.
    Another friend with a 90s 379 as well, showed me a Class 1 inspection he had today and he also had a GVWR of 48,000 with low air leaf. As far as I know, Low Air Leaf was 40k yet they have lower GVWR than my Flex Air.
     
  9. Last Call

    Last Call Road Train Member

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    Low leaf has a higher rating than Flex Air
    Pernsonaly I don't care for flex air more wear points I think they ride worse and it weighs more than a low leaf
    I have yet to see any sort of advantage to flex air
     
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  10. Sandsailor

    Sandsailor Bobtail Member

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    I agree about the wear points, I haven’t driven a low air leaf in 8 years so I can’t really compare the ride. Only thing I have against flex air is they lean a lot on curves.

    but my truck is lighter, with a heavier engine, I think the Flex Air is supposed to be 400 pounds lighter.

    my big question was on weight ratings, but according to Peterbilt they gave Flex Air a higher axle rating than both of the low air leaf that I looked at. So I keep scratching my head about the tandem weight limit.
     
  11. AModelCat

    AModelCat Road Train Member

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    They probably make the suspensions in different weight ratings.
     
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