What can I tow? A real world example

My in-laws have gone camping with us a few times these past couple of years and have gone to the RV shows with us (first as we were looking to buy a camper and now as we go to oogle the campers and lust over accessories). We’ve walked around and they are interested in getting something.

Their current vehicle is a 2006-ish Toyota 4Runner with a V8 engine and advertised 7,000 lb. towing capacity. My father-in-law has heeded my warnings of, “That’s in a best case scenario” to “That’s unlikely realistic” and asked me outright, “So, what can I tow?”

Similar to my page on the same topic, here’s what I sent to him:

Long story shortest, you should be able to tow a trailer with a maximum weight of between 4,000 and 4,600 pounds (depending on what all you carry in the 4runner with you).

Read on if you want to figure out how I got to there and what to look for as you look at campers.

Here’s a photo that I took of your placards on the doorjamb:

The important part of this one is where it says, “The combined weight of occupants and cargo should never exceed 950 lbs.” This assumes a full tank of gas and a 150 pounds passenger. (Note, as of posting this, I realize we have to check his manual to see if this is a true fact or not.)

Travel trailers are best behaved on the road when they have between 10% and 15% of their entire weight on the tongue. This weight counts toward your cargo carrying capacity and is the true limiting factor. To hit the theoretical 7,000 pounds of towing capacity – you would have to be 150 pounds, carry no passengers or gear and have a tongue weight of 13.5% (7000 * .135 = ~945). You have to be careful with tongue weights as going to low can induce trailer sway. You can combat that somewhat with friction control devices and fancier hitches, but they all come at a cost of their own weight. Our pop-up required a sway bar, I had a harrowing experience my first trip out I-70 by myself with it. Be aware of it and don’t go too light for the pure basis of getting a bigger trailer. For me, I would plan for as low as 13% but no lower.

So now, looking at your real world guesstimates:

• You and passengers will be about 250 pounds
• You’ll carry a cooler, some clothes, some random other stuff for another 75 pounds
• The hitch receiver and various hitch hardware is maybe 25 pounds

Best guess ballpark is 350 pounds. That leaves you with 600 pounds of remaining cargo carrying capacity.

Doing the math backwards at different tongue weights gives you:

• 15% tongue weight = maximum trailer weight of 4,000 pounds
• 14% tongue weight = maximum trailer weight of 4,285 pounds
• 13% tongue weight = maximum trailer weight of 4,600 pounds
• 12% tongue weight = maximum trailer weight of 5,000 pounds
• 11% tongue weight = maximum trailer weight of 5,454 pounds
• 10% tongue weight = maximum trailer weight of 6,000 pounds

Now, the next challenge is what number do you pick from the RV manufacturer to go off of. Every manufacturer describes and tries to sell on the “dry weight” (or even the dry hitch weight) – both of these numbers are fallacies. Many times, these are measured before propane tanks are added/filled or battery is added, etc. It’s just not a realistic number. The most definite number is the “Gross Vehicle Weight Rating” (or “GVWR”). This is the absolute maximum that the trailer can/should ever weigh. This is a more constant number and if you go off of this, you know you won’t overload your vehicle.

Many manufacturer websites stink and aren’t up to date/fully filled out. See this screenshot from the Rockwood MiniLite website:

I’m not sure why they haven’t filled in the GVWR as it should be simply the unloaded vehicle weight (aka “dry weight”) plus the cargo carrying capacity (CCC) – 3,630 + 1,088 = 4,718 lbs. Which puts it just a bit higher than you may be willing to go (depending on what tongue weight your end up with).

What was nice about this exercise is that it will help us dial in a specific trailer that matches his tow vehicle and they both can be happy with.

(Note: a special thanks to TrailerTraveler.net for the beautiful image at the top.)