A couple things to keep in mind:
- For every action, there's a reaction.
- The rear axle of the tow vehicle and the trailer's axle(s) are fulcrum points.
With the above said, any weight added to an area of a trailer or tow vehicle will have an opposite effect to the other side of that axle.
Examples:
- Hitching your trailer to the tow vehicle. The tongue weight of the trailer puts downward force behind the rear axle (fulcrum point). In turn, the front of the tow vehicle slightly raises up.
- Changing the tongue weight of the trailer can easily happen from the rear of the trailer. In this case, the trailer's axle(s) act as the fulcrum point. By adding or removing weight at the rear of the trailer, the tongue will see the opposite.
My personal example of this was increasing tongue weight by removing the factory mounted bike rack on the bumper of the trailer. The rack weighed 82 pounds and was 129" from the trailers axles (fulcrum). By removing the 82 pounds off the bumper, this put more downward force on the tongue. With the coupler being 225" from the axles, this resulted in 47 more pounds of tongue weight.
Think of it as 2 kids weighing different amounts on a teeter-totter. Two equal weight kids can be equal distance from the fulcrum point and balance. two kids with different weights have to be different distances from the fulcrum point.
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2017 Forest River Surveyor 247BHDS...
...Tugged by a 2016 F250 XLT FX4 SuperCrew, Shortbed 6.2L, 4wd, 3.73...
...Joined with a Husky Centerline TS 800-1200lbs WDH