I’m somewhat active in various online RV communities, and it never fails to amaze me how people can be easily manipulated into purchasing a trailer that is unsafe to tow with their vehicle. Or even better are the people that show up with an unsafe combination and try to justify it, “but the towing capacity is 10,000 pounds”. What most do not realize is the numbers are cooked in all manner of ways, starting with a basic understanding of the terms Towing Capacity, Tongue Weight, Payload and Axle Ratings. Towing Capacity in particular may not mean what you think.
Further RV manufacturers actively confuse things (and IMO outright lie) about numbers, they get away with this by including “specs subject to change” in all marketing materials. I cover that in more detail in When Optional = Mandatory.
Towing Capacity: is the weight your vehicle could pull. If you had a trailer with 4 wheels and no weight on the trailer hitch you could tow the max…. however when was the last time you saw one of those? Yup, only large haul trucks.. There are no travel trailers made that way.
Tongue Weight: In order for a trailer to tow safely there must be a certain amount of weight on the tongue, generally 12-18% of the total trailer weight. In effect the trailer is a giant lever and if you don’t have enough weight up front it could literally lift your rear wheels off the ground when going over bumps. Your vehicle will have a max tongue weight rating that should not be exceeded, and if you read the details you will also likely find that in order to carry more than a certain amount of tongue weight you must have a weight distributing hitch installed (and installed properly).
Payload: THIS IS GENERALLY THE MOST IMPORTANT NUMBER. You need to know the payload of your specific vehicle, as equipped with a full tank of fuel. There is a sticker on the drivers door jam that will list the available payload for your specific vehicle as delivered to the dealer. You will need to subtract any dealer/customer accessories (running boards, massive subwoofers, etc). Then you need to subtract the weight of everyone and everything that will be in the vehicle. You will quickly find that your available payload is considerably less than the manufacturer claimed in the brochure, that’s because the brochure numbers are from a fictional ‘base’ vehicle that is never delivered. The ONLY way to know your actual numbers is to get your tow vehicle weighed loaded up for a trip and subtract that from the GVWR (Gross Vehicle Weight Rating) for your specific vehicle.
Axle Ratings: To further confuse the uninformed consumer you need to be wary of axle ratings. Each axle has a rating for the maximum it can carry, exceeding those values would not be recommended.
Now you have an understanding of the ratings you should know, perhaps you are wondering why you should care? If you were to get into an accident that results in significant injury or death, you can bet the insurance companies are going to look for any way they can avoid paying out. Making sure your towing setup is within limits set out by the manufacturer is up to you.
Example using our Ram 1500 and Econ 16RB trailer
Towing Capacity: 10,200# (er, yeah…)
Payload: a bit over 1,300# (due to 4×4, large fuel tank, club cab..etc).
Axle ratings front and rear are both: 3,900#.
TT Axle Weight: 2,700#
TT Tongue Weight: 550# (both actual scale weights).
Remove tongue weight from payload and we have 750#, remove WD hitch weight (80#) and we’re left with 670# for ourselves and cargo. Sound like a lot? It’s not really, even if we were average sized (my wife is however I’m in the big and tall department) say 180# man and 140# women you would only have 350# left for firewood, portable generator, cooler full of beer/ice, extra water, etc…
You can easily see that we are within the ratings, however we don’t have much wiggle room on payload. Our setup tows like it’s not there, we often take trips up into the mountains on twisty steep roads and it hauls/brakes very nicely.
Notice how my 10,200# towing capacity translated into an actual trailer weight of a bit over 3,000#? What the heck happened to the other 7,000 pounds of towing capacity?? It was never there except on paper.
There are slightly different calculations for fifth wheel trailers however many of the same problems remain.