New TT Weighing Process?

[Teamfour]

Last time I had a TT the process was to weigh the TT and truck together with the WD bars installed and then weigh the truck by itself. I would subtract the truck weight from the combined weight of the two truck axles when hooked to the TT to find the tongue weight.

Now I see folks saying to perform three weighings. The two I described and a third time with the TT hitched up but with the WD bars in the bed of the truck. I assume this would give me the numbers to get the "true" tongue weight? If correct, why should I care? I am really looking for the tongue weight as towed, correct?

Can someone clear this up?

[Teamfour]

Mickeyfan0805 wrote:

Teamfour wrote:
Thanks to both of you! It makes sense now.

I have been estimating my weights (I will get a chance to actually weigh this Friday) and came up with 900 true TW (12% of TT wt) based on a TT loaded weight of 7500. If I read APT's post correctly, my TW with the WDH hooked up may only be 720 at the hitch?

I'm not 100% sure I understand what you are saying, but it sounds as though you are estimating a 900 pound TW based on a simple 12% estimate of a 7,500 pound trailer (simple estimated calculations with no real weights involved). If that is what you are saying, the rest of your statement is very close, but with one clarification.

Your TW at the hitch is your TW at the hitch - the WD hitch does not change that. There are only two ways to accurately get a TW - by weighing the truck alone and then then truck with the TT attached but WITHOUT the WD hitch engaged, or by using a TW scale. Either way, the result is your 'true' TW, regardless of any WD system. This is the number that should be in that 12-13% range of total trailer weight, and is the number that applies to the rating on the hitch of your TV (the max WD rating is for your TOTAL TW before WD is engaged).

Where the WD redistribution comes into play is in axle ratings and payload (RAWR and GVWR). While your tongue may be 900 pounds, it is possible that, once WD is engaged, the effect on the total weight of your TV may only be 80% of that (the other 20% being redistributed to the TT axles). In such a situation, then, you are only using 720 pounds, instead of 900, of your available payload. Especially in 1/2 vehicles, this can become an important factor.

That is what I thought but you were able to word it so much better.

[myredracer]

Another reason to get an actual/true tongue weight is to ensure that your spring bars are correctly sized.

I had no end of trouble setting up our new Reese WDH last year until I went to a scale and discovered that the tongue wt. was nearly double the factory figure. New set of next-size-up bars worked great.

[brulaz]

Teamfour wrote:
Thanks to both of you! It makes sense now.

I have been estimating my weights (I will get a chance to actually weigh this Friday) and came up with 900 true TW (12% of TT wt) based on a TT loaded weight of 7500. If I read APT's post correctly, my TW with the WDH hooked up may only be 720 at the hitch?

Yes, and that may be useful if your tow vehicle is exceeding its GVWR (payload) or rear GAWR. But as Apt mentioned, you want the "true" tongue weight to compare to your receiver's rating.

It seems that WDH's, on average, put 20% of the tongue weight back on the trailer wheels. But that's just an average. Your actual numbers can be calculated after doing the 3 stage weighing. My WDH put only 12% of the tongue weight back on the trailer wheels. But I've tightened it up since then and expect more next time I weigh.

[Mickeyfan0805]

Teamfour wrote:
Thanks to both of you! It makes sense now.

I have been estimating my weights (I will get a chance to actually weigh this Friday) and came up with 900 true TW (12% of TT wt) based on a TT loaded weight of 7500. If I read APT's post correctly, my TW with the WDH hooked up may only be 720 at the hitch?

I'm not 100% sure I understand what you are saying, but it sounds as though you are estimating a 900 pound TW based on a simple 12% estimate of a 7,500 pound trailer (simple estimated calculations with no real weights involved). If that is what you are saying, the rest of your statement is very close, but with one clarification.

Your TW at the hitch is your TW at the hitch - the WD hitch does not change that. There are only two ways to accurately get a TW - by weighing the truck alone and then then truck with the TT attached but WITHOUT the WD hitch engaged, or by using a TW scale. Either way, the result is your 'true' TW, regardless of any WD system. This is the number that should be in that 12-13% range of total trailer weight, and is the number that applies to the rating on the hitch of your TV (the max WD rating is for your TOTAL TW before WD is engaged).

Where the WD redistribution comes into play is in axle ratings and payload (RAWR and GVWR). While your tongue may be 900 pounds, it is possible that, once WD is engaged, the effect on the total weight of your TV may only be 80% of that (the other 20% being redistributed to the TT axles). In such a situation, then, you are only using 720 pounds, instead of 900, of your available payload. Especially in 1/2 vehicles, this can become an important factor.

[Teamfour]

Thanks to both of you! It makes sense now.

I have been estimating my weights (I will get a chance to actually weigh this Friday) and came up with 900 true TW (12% of TT wt) based on a TT loaded weight of 7500. If I read APT's post correctly, my TW with the WDH hooked up may only be 720 at the hitch?

[APT]

A WDH will put some tongue weight on the trailer axles, which seems near 20% for those who have measured their TT weights. So what you call true tongue weight is tongue weight and what you measure is only the amount of TW carried by the truck's axles.

Here's an example:
TW measure by something like a Sherline scale: 1000 pounds
Drop the tongue on the ball:
Front axle decreases by 400 pounds, rear axle increases by 1400 pounds. This is the net 1000 pounds of TW.
Now apply WD to restore 100% of front axle weight:
Front axle same as unhitched, rear axle is now only 800 pounds, and trailer axles went up by 200 pounds.

So the efffect of TW on the truck's axles is 800 pounds which goes towards payload/GVWR. The effect on the receiver is 1000 pounds which should be checked vs. its limit.

[brulaz]

When people say you should have 12% or 13% or whatever % tongue weight, they are referring to the "true" tongue weight relative to the total trailer weight.

You need to slack the tension bars to get that.

But you also want the axle weights with the tension bars tightened up for the actual, operational Gross Axle Weights to compare to GAWRs and so on.