Why Would New Trailer Tire Cause Trailer to Sway

Updated 04/29/2024 | Published 10/01/2018

Question:

I am towing a 22ft. enclosed car trailer, total trailer and cargo weight about 6500 lbs., with a weight distribution hitch and Reese dual cam anti-sway bars. Tow vehicle is Ford F-150 with max tow package. No problems with trailer sway for the last 4 years. But I just put on new Goodyear Endurance tires inflated to 75-80 psi. I previously had no name OEM tires inflated to 55-60 psi I just had a trip where I had 4+ instances of sway from passing trucks while on the interstate. Yes the Ford anti-sway feature did step in, but it was still very uncomfortable. I understand the importance of load balance. The car has basically been loaded in the same position for the last 4 years with no problem, but I thought it may be a little forward this time, so I stopped at rest area to move it back a little bit. That did not help. Still had a squirrelly trailer behind me. Being that the only real change to the set up has been the different tires, I wonder if the air pressure on the Goodyears should be adjusted. Sidewall recommends 80 psi for max load. Maybe 6500 lbs is not a max load and therefore Im riding on over inflated tires and the trailer is bouncing around?

asked by: Jim B

Expert Reply:

Since the only thing that's changed is the tires and now you have sway it's to think it would be anything else. I'd verify that you have the tires inflate to the max psi and also make sure the tires are ST rated. I believe there has to be something off with them.

With trailer tires you have to make sure you keep them always at the max pressure otherwise the load capacity is diminished. The sidewall would also get weaker and possibly flex.

expert reply by: Jameson C

Zane K.

4/27/2024

I’m also experiencing the same problem. I replaced my tires on my 2 axles, enclosed trailer. Original tires are 205/75/15 Load Range D. Tires always seemed overloaded so when I replaced them I was told by the tire shop that I can use Load Range E tires but the only tire size that they carried with a E Range is 225/75/15. The tire shop said it would be okay but now the trailer sways a lot which never used to be a problem!

Jameson C.

4/29/2024

@ZaneK I would check two things. Make sure the tires are inflated to the max psi rating on the sidewall when cold and also make sure that the trailer is still sitting level when connected to your tow vehicle.