It is not just the static weight and force applied by the WD and anti sway systems that should be considered. It is also the G force applied when tires slam into the edge of a pot hole etc. Or, The force of the anti sway system trying to swing the trailer side ways like a baseball bat. Inherently the anti sway systems purpose is to keep the TV and Coach in a straight line. So when you turn, the lateral force on all tires increase extemporaneous, because of the force applied by the anti sway system.
Add to this the Hiway speed, weight of the coach, poor or unskilled towing technics and you have a formula for failure.
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