acadianbob

I think you should be sure of what is going on before you jump to different tires. I've got LT's too, and they work great, but I never had sway with P-metrics; I got vertical bounce. New LT's are going to set you back 1,200 to 1,500. My bet is that the problem will still be there even if you buy different tires.

You have a low profile tire with the 20's. There is even less opportunity for sidewall induced sway than with 17's or 18's.

brulaz

I stiffened the rear suspension as well as switched to LT tires.
IMHO these truck's suspension is too soft for carrying a full load.

2015fordf150

What did you do to stiffen the rear?

5.0GN tow

I don't think with that size trailer it's the tires. I am with most guys here and agree it's in the WDH set up. If the trailer is 5600 wet. Weight on the hitch is probably less than 700lbs. With a proper hitch set up you should be well under the max load for p series 20 inch tires and not over the rear GAWR either. I think you are unloading the hitch to much or actually moving too much weight forward.

2015fordf150

I hope it is not the tires. I pulled this same trailer with a 2004 F150 with LT tires and a F250 with LT tires. The trailer pulled straight without any squirming around.

brulaz

Lots of options.
Timbrens, bags,add-a-leaf,RAS
I use RAS plus an over-size end block to engage the over-load spring earlier. Plus HD shocks. With that and the LTs it would have been cheaper to get the HD payload option.

bmach

I would really start with setting up the hitch again. I'm pulling a 26' trailer that weighs a little more than yours, using the hitch a you are, with no problems at all.

2015fordf150

I have set up the hitch many different way with no success. Been pulling camper for 20 plus years with no problems till I got this new Ford F150. What truck do you have? What size and type tires? P or LT
Hooked to friends F250 and pulls straight as an arrow.

Loki 5.0

Is the trailer nose down , level or?

2015fordf150

Close to level, Might be slightly down in front.