Your rig may be overloaded

I recently did a deep dive into vehicle loading, and discovered that it is much easier to overload a vehicle than one would think.  It seems like a simple calculation: get a vehicle and/or trailer large enough to accommodate everything you need for a show, then make sure that the tow vehicle and hitch are rated to tow the weight of your trailer plus a guestimate of the weight of your gear, and you’re done.  My tow vehicle is rated to tow a 5000 pound trailer, and my fully loaded trailer weighs right around 2000 pounds.  Yet it turns out that my setup is right at the overload limit, and I need to be careful what additional items I take to shows, and where I put them. 

The problem appears to be that car and truck makers compete with each other on how much their vehicles can tow, so the advertised tow rating is actually a marketing number that assumes that the vehicle is empty except for perhaps a light-weight driver.  Load it up with two people and a weekend’s luggage and supplies, plus the tongue weight of the trailer, and the weight one can safely tow drops significantly. 

I calculated the weight of my cargo by putting a bathroom scale and notepad next to the trailer and tow vehicle  simply weighing everything before it was loaded.  I measured tongue load by lowering the tongue jack onto a board supported by a brick on one side and the bathroom scale on the other, doubling the results. When I tallied up the total, I was quite surprised at how relatively light items add up.  I calculated safe loading based on the method describe in my owner’s manual (which varies somewhat between manufacturers).  Finally, I consulted www.karavantrailers.com/brakes/Brakes.xlsx to determine if my unbraked trailer was too heavy for the states I operate in.  You may want to do the same for your own safety and well being.

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  • As I have at times, lost self control with those that desperately needed and received a verbal bashing, I guess I should have monitored my "tongue weight" also  :-)  Sorry, I could not help myself.

    Now I usually drive my Avalanche to the shows. Towing is a dream with it. It has so much weight of it's own. Handles great when towing. Stopping is lousy, even though I've upgraded the brakes with a Hawk system.

  • Your Rabbit story is funny.  I have pulled U-Hauls with my Toyota Corolla and boats with my Camaro Z-28.  Fortunately, God protects the innocent …

    Yes, the proper way to measure tongue weight is right at the coupler with the trailer level.  My tongue jack is mounted in the triangle right behind the coupler, so I thought it good enough to approximate the tongue weight for my purposes.

    Tongue weight turns out to be a critical parameter.  Either too little or too much can kill you.  Too little, and the trailer will pick up the back end of the tow vehicle, causing it to swerve out of control as Robert’s video illustrated.  Too much, and it will pick up the front wheels, causing loss of steering.  With that new-found insight I plan to monitor my tongue weight much more carefully than I have in the past.

  • Many years ago, I had a VW Rabbit (in the 70's). I had heavy duty roof racks. I put a lot of cement in the vehicle and a lot of lumber on the roof. Sure the car sank low, but I thought I would drive slow...

    I blew out both back tires.

    Yup, way over the GVWR, as well as the tire load rating.

    Years later I did take one of my F250 trucks. Had a very good shop who specialized in trucks beef up the suspension. I put 1 1/2 ton on the rack system and 2 tons in the bed, making the back cargo at 3 1/2 ton. Then add all the construction tools and men in the truck, I had no problem driving up extremely steep hills with that beast.

    Way illegal but it worked well. Handled fine. Put over hundred thousand miles on it without any issues at all.

    That truck and rack still sit at one of my properties. I have not used it in years. I should sell it but it treated me so well. Again, I was wrong for what I was doing with that truck but the more weight in that baby the more it liked it and handled great.

    I'm no expert on trailering or hauling by any means.

    Doesn't tongue weight have to be measured in a specific way? I would think how the load is put into the trailer and the angle of attachment to the vehicle will affect what tongue weight is achieved.

  • Really informative, Robert. A little frightening also. Thank you — a real service
  • I thought I might toss out this video I ran across a while back that shows the effects of improper loading.
    https://www.facebook.com/grownmenstuff/videos/1880365532213332/

  • Just an observation, I have been doing body work on my '88 suburban and '2013 Subaru. Also read that some PU's are going to aluminum bodies. The difference in thickness of steel body parts is alarming to me. I'm patching and rebuilding with 20 and 18 ga. You could hardly use a sling hammer on Subaru it was so thin. A heat gun might have popped dents better LOL. Anyways, the lighter metal and weight is going to affect GVW and handling with loads. I will keep my '88 Suburban on the road the rest of my lifetime. Intersting read Reid Watts.

  • Connie – My sources of information were trucking sites (whose members are forced by weigh stations to live within the regulated weight ratings for their rigs), RV sites, and manufacturer’s user manuals (almost all of which can now be found online).  I did a deep dive because I was in the process of replacing my tow vehicle, and wanted to make sure my new vehicle safely met my needs.  When I was done it occurred to me that many artists are probably overloading their vehicles and are unaware of it.  Hence the post.

    It’s not hard to overload.  My tent poles and hardware, weights, and battery add up to almost 600 pounds.  Add in 300 pounds of tongue weight, the weight of the driver and partner and you are easily at 1200 pounds without even starting to include artwork, baggage, etc.  1200 pounds turns out to be a pretty good “payload” for the vehicles we mostly use (half ton trucks or vehicles based on them).  One SUV I looked has a payload as low as 882 pounds (which is still workable with a small trailer, but you have to be very careful on how you spread the load and how much total load you carry).

  • I know each of us has pockets of knowledge that surprise each other, but Reid, this is such specialized info, how do you come by it?
  • I checked it out with my mechanics, and truck handles much better.

  • Richard - Just to make sure nobody is misinterprets your story:  Adding additional springs or airbags may make a truck more comfortable while operating at or very near its GVWR (Gross Vehicle Weight Rating).  But it will not increase the payload (carrying capacity).  In fact, it decreases the payload by increasing the curb weight. 

    Background: The GVWR and GAWR (gross axle weight rating) on the certification label on the door jamb are standardized by federal regulation.  Only the manufacturer can set them.  Nothing modified in the aftermarket can change them.  Gross combined weight rating (GCWR) validation covers things like driveline durability and cooling, while GVWR and GAWR validation covers brakes, frame, wheel bearings, springs, suspension arms/bushings, steering pumps and gear, tires, and box integrity.  These components were engineered and tested against those weight ratings.

    That said, the springs on a 1988 Suburban are probably way past their prime, and adding additional leafs can’t hurt.

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