Originally Posted by Okietrucker
Do you mean drop trailer on scale to check tongue?
Yes. You disconnect the hitch, then use the tongue jack to raise the tongue of the trailer enough to clear the ball. Then move the tow vehicle out of the way. Then put the Sherline scale under the coupler and use the tongue jack to lower the coupler onto the Sherline scale. Then read the weight on the scale.
Weight on the scale is the tongue weight.
Weigh the rig on a CAT scale to get the weight on the trailer axles. Weight on the trailer axles is the gross axle weight (GAW). GAW plus tongue weight = GVW (gross weight) of the trailer.
Tongue weight divided by GVW = percentage of hitch weight. Your goal is 12 percent, but anything between 10 to 15 percent is okay. DO NOT
have less than 10 percent, because that can result in uncontrolled sway. More than 15% tongue weight doesn't hurt anything if your tow vehicle has enough unused payload capacity to handle the extra weight.
Example: I weighed my tongue on the Sherline and found the tongue weight to be 650 pounds. Then I weighed the rig on a CAT scale twice, once with the weight-distributing bars hooked up and once without the WD bars.
GVW Front rear trailer
6800 3280 3520 3620 WD (weight distributing)
6920 3040 3880 3480 WC (weight carrying)
---- ---- ---- ----
. 120 240 (360) 140 difference
So the WD hitch moved 360 pounds off the rear axle, including 240 pounds from the rear axle to the front axle of the truck, 140 pounds from the ball to the trailer axles, and left 290 of the total 650 pounds hitch weight on the ball. (There's a 20-pound CAT scale error in those numbers, but it's insignificant.)
3480 trailer axle weight WC, plus 650 pounds hitch weight = 4,130 gross trailer weight. 650 divided by 4130 = 15.7% hitch weight. Later weights show it is closer to 15% after several thousand miles of towing.