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Walaby's avatar
Walaby
Explorer II
Mar 20, 2019

Effect of weight in rear of 5er

Is there any estimating rationale for determining how much effect adding weight BEHIND the rear axles of a 5er has on the pin weight? I would imagine it's perhaps close to 1:1, but not sure.

My fresh water tank is completely behind the rear axle of my Reflection 367BHS. Right now, Im at 22% pin weight (with no water in my fresh tank). Plan on carrying ~10-15 gals of water (~80-120 lbs), so just curious if that will result in an offset an equal amount of pin weight or what?

I'll probably weigh with water to make sure but just curious what others have experienced.

Thanks in advance.

Mike

10 Replies

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  • naturist's avatar
    naturist
    Nomad
    Mar 21, 2019
    (Weight in pounds)x(distance from center of tank to center between trailer axles) = (distance from center between axles to hitch pin)x(pounds off pin weight). This is a simplification and therefore only a rough estimate. And I agree, if tank is only a short way behind axles, 100-200 lbs of water is negligible.
  • azdryheat's avatar
    azdryheat
    Explorer
    Mar 20, 2019
    If you read up on Weight and Balance, that airplane pilots have to know, you could compute the exact amount of weight effect on your pin.
  • Walaby's avatar
    Walaby
    Explorer II
    Mar 20, 2019
    Thanks guys...

    Makes a lot of sense thinking about it.

    Mike
  • ACZL's avatar
    ACZL
    Explorer
    Mar 20, 2019
    So your going to have 100# of water +/- regardless of where it is. Really don't think you have much to worry about where it's going to be placed and it's affect on the TV. We've dry camped w/ 60 gallons both in old coach and new one. Went 100 miles one way and to be honest, never noticed a difference on where the water was.
  • valhalla360's avatar
    valhalla360
    Navigator
    Mar 20, 2019
    As long as it's close to the axles, likely won't have any noticeable impact.

    But:
    - Take the distance from the center point of the axles (combined no matter the number of axles) to both pin and center of water tank.
    - Divide water tank distance by pin distance.
    - Multiply that by the extra water weight.

    You can do this for any weight added to the trailer (works for bumper pull trailers also just replace pin with the ball socket distance)
  • Me_Again's avatar
    Me_Again
    Explorer III
    Mar 20, 2019
    With our 29' Cardinal, I could notice a pretty big difference when dry camping when the fresh water in the very rear was moved to the grey(2) and black tanks ahead of the axles. So not only did I remove weight from the rear of the axles, I added weight ahead of the axles. 60 gals of fresh plus recycled beer! Chris
  • SailingOn's avatar
    SailingOn
    Explorer
    Mar 20, 2019
    If your fresh water tank is immediately behind the rear axle, its center is likely 6 feet or so from the fulcrum between the axles, and 20 feet or more from the pin, so a ratio of 6/20, ie 1/3 or less.
    100 pounds of water, about 12 gallons, then would reduce the pin weight by 30 pounds or likely less.
    Note, though, that if you put a LOT of weight in the rear you increase fishtailing.
  • enblethen's avatar
    enblethen
    Nomad
    Mar 20, 2019
    You need to calculated the ratio of rig in front of axles to the amount behind the axles. Weight of fresh water would need to be from centerline of water tank to distance front axle to rear of rig.
    I would guess that it would be 10-15 percent. Not enough to drastically change pin weight.
  • JIMNLIN's avatar
    JIMNLIN
    Explorer III
    Mar 20, 2019
    Having loaded many flatdeck trailers with freight and loaded many stock trailers I've found its certainly not a 1:1 ratio.
    Keep in mind a trailer doesn't act as a teeter totter with a single pivot point.
    A tandem trailer axles can be 6'-7' between the farthest front and aft spring hanger....and not all trailers have the same rear overhang or pin distance to the trailers first axle or the same trailer length.
    Also placing weight just behind the aft axle or out to the end of the frame.

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