oilspot

To answer your question, most sway is usually due to not enough weight on the tongue (i.e. too much weight to the rear) or poor trailer design.  Since TM carefully designs to eliminate sway, try redistributing the weight in the trailer to cure the problem.

I don't recommend adding any more than the max pressure listed on the tire sidewall (usually ~50psi).  Be sure to check tire pressure when cold, as the pressure will increases with use (heat).

As a caution:  There is no danger using a sway controller on a trailer that has no sway problems.... many people on this board do this.  (I have one but have never installed it)  However using a sway controller on a trailer that has a true sway problem can make matters even worse.  Sway controllers often mask symptoms (not cure them) until the sway gets out of control.