Hitch weight with a bathroom scale

**CanoeStream** · 07-08-2006, 11:47 AM

We've talked about this method and the diagram is in many Airstream manuals. I think it is high time we had a better point of reference in the Forums. This will be a how-to for using simple materials and a bathroom scale to weigh the hitch (a.k.a. tongue) weight. Refer to the diagram attached to this post.

Do this only with the trailer on level ground and wheels chocked. Make sure the scale is capable of weighing at least 250 pounds (300# better). You can weigh 2 to 4 times the scale capacity with this setup, therefore you might be able to make this measurement for up to a 30-footer depending on vintage (newer trailers being much heavier). Refer to Airstream's FAQ page numbers on your trailer's curb weight (without options). This simple measurement will help you understand where your tongue weight falls in relation to the empty trailer number. For real world relevance I would advise having WD gear & your bars on the A frame, having LP in the tanks, and even taking the hitch bar/ball off your TV and setting it on the A frame too (we are aiming for the tongue weight load imposed on your TV after all). Whether you have any personal items in the trailer is up to you -- just factor in an allowance if the trailer is empty. Weighing at a CAT truck scale should be more accurate than a bathroom scale; use the search function if you want to find more on that.

These instructions from Draw-Tite are clear and I don't want to put this off until I can retrieve the manual from our stored trailer.
"Tongue weight (TW) is the downward force exerted on the hitch ball by the trailer coupler. In most cases, it is about 10 to 15 percent of GTW. TW of up to 300 lbs. can be measured on a household scale by resting the trailer coupler on the scale and placing the scale on a box so that the coupler is at its normal towing height. The trailer must be fully loaded and level.

"For heavier tongue weights, place a household scale and a brick that's as thick as the scale three feet apart as shown in Figure 2. Set a length of pipe on each and rest a beam across the pipes. Re-zero the scale to correct for the weight of the beam and pipe. Securely block the trailer wheels. Rest the trailer jack on the beam as shown, one (1) foot from the brick and two (2) feet from the scale.

"To obtain the TW, multiply the scale reading by three (3). For greater tongue weights, place the scale and brick four (4) feet apart, rest the jack on the beam three (3) feet from the scale and multiply the scale reading by four (4)."

Be sure and use beefy enough lumber and maybe put a piece of plywood on your bathroom scale to spread out the forces concentrated under the pipe.

**Chuck** · 07-08-2006, 12:00 PM

what's the pipe for?

can't really see it in the drawing, either.

**CanoeStream** · 07-08-2006, 12:03 PM

Due to the widths of the scale and brick, the two pieces of pipe allow a very measured fulcrum point to be set up so that the geometry allows accurate weights. Honestly, I don't think you'd be off much if you ripped a 3/4" square length of wood to substitute for the pipe.

I can probably say I wouldn't put the pipe on a brick unless there was plywood underneath to spread forces. Probably better to skip the brick if you just stacked wood pieces until you equalled the height of the bathroom scale. Also -- put the scale on some solid surface, not sand it might sink into.

Excella CM · 07-08-2006, 03:47 PM

If you want to get crazy, you could substitute two pieces of angle iron for the two pipes. Place them open side down and you have two knife edges!

scottanlily · 07-08-2006, 10:50 PM

hello canoestream ,

The bathroom scale things seems kinda kooky ,but I did try it with my 60
trdwnd and the tongue weight as listed in the airstream archives trailer
weights show 310# and I measured 320# so pretty close .Haven't tried it
ready to go though. When I get a chance sometime .

Scott

**CanoeStream** · 07-09-2006, 09:41 PM

Thanks for giving us some real-world results Scott. I will weigh my 25' Safari next weekend and report results here. Anybody else?

I feel that something approaching loaded tongue weights could be a surprise to some readers if they rely on the specifications published in their owners manual or at airstream.com. Those specifications do say that it is for the unloaded trailer without options; for instance, the current Safari LS package (which I have) does include a spare tire that is located very close to the underside front of the trailer.

Stay tuned.

safari57 · 07-10-2006, 12:36 PM

Lessons learned:

1. If you are using the scales out of the ensuite, those would be the formerly all white ones, consider wrapping them in something to protect them from scratches and put something under them so dirt does not get caught up in the no slip pad on the bottom.

2. If you are using those same scales, before you put them back, clean them and then clean them some more, remove as many of the "oops" as you can, and get them back into the exact same spot BEFORE your spouse (wife) comes home. Particularly if said spouse has a known "everything must be clean and orderly" fetish.

3. It is not advisable, when said spouse goes to use the weigh scales and notices they have been used in a manner that does not fit with her Clean Homes and Orderly Gardens weigh scale usage criteria, to suggest that perhaps the scuff marks are because she's maybe gained a few pounds and is now putting a tad more stress on the old scales. Other no-no comments would be how surprised you are that they've survived as long as they have, or musta been when her mom/sister etc was out visiting.

4. It is important to note here that it is almost impossible to dodge a set of weigh scales coming at high velocity in the limited confines of the ensuite after any of the statements in #3 are vocalized. It doesn't matter how fast you think you are. There's a unique ricochet effect that comes into play that said spouse seems to be well versed in - I think they learned that in HomeEc in school. It can be deadly!

5. Be prepared to purchase a new set of weigh scales and there's always the probability of wall repair (glancing blow) and bruising. As for eardrums, I'm told that eventually they may heal.

Solution: Borrow your neighbours. Don't tell him why. Let him live with the consequences. It's one way to get even for all those tools he's borrowed and "forgotten" to return.

Barry

**Chuck** · 07-10-2006, 01:17 PM

good tips!!

you may also want to "re-zero" the scale when you're done, should you choose to forego the previous advice...