BlackBoost

I keep reading about the 10-13% rule of trailer tongue weight. Is it different for tandem axle trailers?


My trailer is around 5000lbs loaded. It's old and heavy, has a big Mach15 air conditioner, and it's a 1988 so it was built before all the ultralite's. I also bring tons of tools, jackstands, 3-ton jack etc in the camper's storage compartment in case I need anything on the road.


Without water in the tank, which is at the front, my tongue weight is 350 lbs. My fill is around 20 gallons, like 165 lbs, so add half of that to the tongue weight when full.


I measured the height from ground to fender with and without trailer, in the exact same spot, and with a full tank of gas. The rear fender dropped an inch with the trailer hook up. The front didn't drop or raise at all.


I don't use a swaybar or WDH. Trailer pulls straight, doesn't bounce around or sway even with the sway control option off.


So my question is, are the tongue weight rules different with a tandem? I know the axles carry weight better, and it seems like the trailer is very well balanced.

Simnut

To my eyes....you have a little sag on the truck and more sag forward on the trailer. Could be an optical illusion but if it isn't...wouldn't be the way I want to drive. I think you may have the trailer dictating a little too much which way the truck goes

smokeywren

For a tandem axle trailer, 10% to 15% of wet and loaded gross trailer weight is acceptable for tongue weight. But normal is 12% to 14%, with 13% being the average.

On mine, gross trailer weight is 4870 with 650 pounds hitch weight when wet and loaded on the road. That's 13.47% hitch weight.


Not heavy at all compared to my 2012 ultra-lite with less than 20' floor length that weighs 4,870 when wet and loaded on the road.



Something is not adding up here. If your trailer grosses 5,000 pounds but has tongue weight of only 350 pounds, that's only 7% tongue weight. Dangerous.



Weird. The front fender should have go up at least a bit.

Dangerous. You probably just haven't encountered severe sway-causing or bounce-causing conditions yet. If the trailer weighs 5,000 pounds, the tongue weight should be over 500 pounds, and that much tongue weight requires a weight-distributing (WD) hitch. And any decent WD hitch will include built-in sway prevention/control.

I don't think so. It's much more difficult to have a perfectly-distributed weight in a single-axle trailer than in a tandem-axle trailer, but the final result should be the same = 12 to 14% of gross trailer weight should be on the ball of the hitch.

acdii

There are two answers to this question. A tandem with weight fore and aft of the axles, such as a travel trailer, the answer is yes TW is very important, but trailers such as a horse trailer, or a boat, the TW is pretty much locked in as the mass of weight is for the most part centered on the axles.

Boat trailers are balanced once when the trailer is setup for the boat and pretty much stays that way. The CG of the boat should be centered on the axles, so the TW wont change no matter how many times the trailer is loaded and unloaded.

Horse trailers have the mass centered on the axles as well, and no matter how heavy the horses are, the TW changes very little. Those with a tack room up front are the ones that you do need to be careful with as you can overload the ball, but for the most part, you wont. Another thing with a HT, hookup and go, the TW is pretty much good whether it is completely empty or loaded. On most horse trailers, there is very little weight behind the rear axle, and it doesn't change except when loading and unloading, so no worry about it being tail heavy and becoming a sway monster.

So in these cases, TW is what it is, so packing them isn't critical. Trailer with sapce in front and behind the axles though, become critical to load properly and these are the ones where you do need to be diligent on how much TW they have since they can easily be loaded to light or too heavy.

mass-hole

The tires on that trailer look pretty close to centered on the trailer body. I think most trailers these days have their axles set back a little farther:




I wonder if that is playing a role in the trailer stability and tongue weight.

MichaelInCalifornia

OP,

Also note you need the trailer level. Without it being level, you are loading the front axle more than the rear.

BlackBoost

Rear drops an inch, and it drives like it does without the trailer, even over bad bumps and dips, rough railroad crossings, horrible secondary highway bridge transitions etc



I know it's an odd setup, which is why I posted in the first place. Because it does drive well. And as for sway/bounce causing conditions, you've obviously never been on Alberta roads, especially the secondary country highways lol I have also swerved a couple of times to avoid road debris, and driven in strong side-winds. She's steady as can be. According to the towing screen I've put 1600 on it so far with no problems at all.


I also don't understand why it's so light when it uses a 2-5/16th" ball and has a tongue with 10,000 lbs stamped on it. Looks like it was really overbuilt.


Yeah the A/C unit is directly over the wheels, and the bathroom is at the back wall. The stove/oven is over the rear wheel and the fridge and furnace are just behind the rear wheel.

I have a straight hitch, no drop or lift. I'm not sure if I'd want to get a higher hitch because that might give even less weight on the hitch... Not sure if they make ALL tandem suspension like this, but the leaf shackles are attached to a swing arm in the middle so that they can be uneven but still carry equal load. I just picked it up from an RV Service shop yesterday (when I took the pics at the scales) and they repacked the bearings and installed new suspension shackles. They inspected everything and it all passed, including checking it when it's hooked up to the truck. All they had to do was change how the breakaway cable was running through the hitch because it could snag under the propane tank cover or something.

MichaelInCalifornia

Hitch height has no bearing on tongue weight.

Hitch height does have a roll in how you set up a conventional WD hitch (tilt of the head), which you are not using.

BlackBoost

I mean because of how it all seems to be balanced on the wheels. At least how it is now, it leans forward a bit. Some heavy high center of gravity objects over the axles, like the AC unit, will give a bit of extra weight towards whichever way the trailer is tilted.

Might try a higher hitch and see how it pulls, with and without a full water tank. The tank gives me an extra 80-90 lbs on the hitch when full.

mass-hole

It will to some extent. Think about trying to do a pushup. If you do it with your hands on a chair and feet on the ground its fairly easy. If you then put your feet on the chair and hands on the ground its a lot harder.