New trailer tires and sway

[BTown801 26]

I towed my boat 3k miles last summer with no sway issues. My boat has 18" moto metal wheels on it, with 255/55/R18 tires. I bought my boat used and the tire pressures were all inconsistent when I got it. I inflated them to all match the highest tire psi which was 35. I had no sway with this setup. On the last trip of the season 600 miles round trip to Powell I accidentally rubbed my sidewalls on a curb and shredded them while leaving town. I stopped by discount tire and bought some new Falken tires of the same size. Discount set the tire psi to 50. The boat swayed all the way to Powell and all the way home. It even set off the traction control system in my tundra. Scared the shit out of me. I lowered the pressure down on the boat trailer tires to 45psi on the way to storage and it still didn't feel super stable. So what do you all set your tire pressures to? I know tires break in over the first 1k miles. Any recommendations? 

[bloodiestcadaver 382]

Did you just do one side? its possible you have some radial tire pulling or tracking issues. having different pressures can cause issues from side to side. but if your new tires can hold up to 50 the ply rating might be different. 

[BTown801 26]

@bloodiestcadaver I replaced all 4.

[bloodiestcadaver 382]

14 hours ago, BTown801 said:

@bloodiestcadaver I replaced all 4.

interesting. Having too much air can make it sway a lot. But I think 45psi should be fine and not make a drastic change. Might just be some shit tires. Tires can change alot about how a vehicle/trailer will ride. Maybe discount will let you change them out for a different brand?

[bloodiestcadaver 382]

also It would not be a bad idea to take a "toe" measurement to make sure nothing bent when you damaged the previous tires. If that trailer is tracking wrong and trying to correct itself, it could feel like this I would think

[Tbag 273]

What's your tongue weight?  My guess is it's too light.  

[BTown801 26]

@bloodiestcadaver when I rubbed those sidewalls on the curb I was only going about 1-2mph. I'm not sure how to do a toe measurement, but I'll look into it. Discount has a standard operating procedure that they inflate trailer tires to the max psi but I think that is based on bias ply trailer tires and these are radials. I think I'll pull it a little further in the spring and see if the tires break in. I've had new car tires that wander around for the first 1k miles or so. If it doesn't stop I'll swap them out.  @Tbag I don't think my boat was loaded any different than the previous miles towed throughout this year. It's possible I guess. I'm putting on some Load E tires on Monday, maybe that will help too. 

[schill38 64]

I've been told on trailer tires to always inflate them to the max PSI and that's what I have always done and have had no issues the last 7 years of owning a boat...

[BTown801 26]

I'm leaning towards what @Tbag said that I was light on tongue weight. It's quite possible that I was light on fuel in the tank for those 2 trips and it reduced the tongue weight.