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waynefi's avatar
waynefi
Explorer
Aug 25, 2022

Tongue weight limits and wdh

What happens with the tongue weight limit when you are using a weight distributing hitch?

My Tacoma says the the tongue weight limit is 650 lbs. Does that mean that if my trailer has a tongue weight over 650 I need a wdh, or that I shouldn’t pull that trailer even with a wdh?

The function of a wdh is to take weight off the tongue, right? How would you even measure the tongue weight with the wdh in place?

My current trailer has a nominal tongue weight of 380, but that is before water, a second battery, etc.
  • The 650 pound limit came from Toyota, so it’s not a limit on the ball mount, etc. It is either the hitch receiver or something about the stability of the vehicle.

    I always thought it was about taking too much weight off of the front wheels.

    Here’s another part of the mystery. The Tacoma’s tow capacity is 6500, the tongue weight limit is 650, exactly 10%. A lot of trucks have that 10% value. Why?
  • IF the 650 is the hitch rating, you have say 700. Get rid of that hitch, put a heavier duty one on.

    If that 650 is max per owners manual, that can be a different ball in this game of what one can do or not do towing wise.

    If OM states say 1000 lbs, hitch is rated for 650, do my option one, replace it!

    Marty
  • waynefi wrote:
    The function of a wdh is to take weight off the tongue, right? How would you even measure the tongue weight with the wdh in place?


    Well, sort of. A wdh transfers load from the hitch ball itself onto the front axle of the tow vehicle and also the trailer axles. Without a bunch of crazy, indecipherable calculations, the only way to really know for sure is to weigh truck and trailer axles before and after wdh hookup. I don't know if the 650 lbs for the Taco is with or without wdh, but it does seem like although Toyota makes tough trucks, the US market ones have soft, squishy springs that probably just about bottom out with 650 pounds right on the hitch.
  • my '19 F150 has 2 ratings
    500lbs if just a ball
    1300lbs if using a WDH

    Calculated weight on the hitch using the 3 pass cat scale method I'm running at 1100 lbs.
  • Typically, there are two ratings.
    - Just the ball: It's usually a lower hitch weight and towing limit.
    - With WDH: It's usually a higher hitch weight and towing limit.

    There are typically 4 bolts holding the hitch to the truck. With just the ball, the rear 2 carry pretty much all the hitch weight and it's multiplied due to leverage.

    With a WDH, the hitch weight is distributed across all 4 bolts (though not perfectly evenly).
  • Some factory hitches give you a rating with and without a WDH. My Ram just has a single max weight which I assume means don't exceed whether I'm using a WDH or not. Your Tacoma is probably the same. If you're really at 380 lbs empty I doubt you'll get it up to 650 lbs loaded assuming your hitch runs around 10%.
  • For a Taco that’s likely the overall rating. But idk for sure.
    And coming from a person who pulls all kinds of things sometimes with trucks that aren’t really big enough for the load, I wouldn’t want much more than that on a midsize truck. For multiple reasons.
  • It means don’t put more than 650 pounds on the hitch! Weigh the tongue fully loaded.