On my most recent cross country trip (St. Augustine Fl. to Lake Tahoe Ca.) I experienced three very serious instances of Fishtailing. After each time , I thoroughly checked my unit for possible mechanical issues. Additionally, I rearranged the weight distribution and made changes to the drag on the Anti-sway bar. After the third incident ( in Nevada) I removed the bikes and rack and made the rest of the trip with them in the trailer. With each occurrence I was on the fine line of loosing control and possibly flipping the unit. I started the trip traveling at my normal speed on open roads at the 65-67 MPH and finished the final 300 miles at 55 MPH.
My six previous crossings were made with a 2014 Tacoma Crew- Cab long bed, 4 wheel drive truck. For other considerations, I recently changed tow vehicles to a 2017 Toyota FWD Highlander. Although the ride, power and gas mileage was great, I'm starting to think that the new vehicle is the source of my problem.
When the fishtailing started, I started taking my foot off the gas and gently pumped the brakes---. Should I have tried to apply the trailer brakes? Speed up?? Is there a recommended procedure for this?
I'm unnerved and in desperate need of some answers here or I'll need to sell the unit and leave it in California.