I bought new tires for the Ford 250 and now both the LQ and flatbed trailers slightly fishtail at times when I pull them.  The tires are Goodyear Wrangler AT/D2.  I am assuming that the tires are the reason because I never had this happen before.  It's slight, but scary and I'm not the only one who has noticed it.  It seems to happen mostly when turning a corner, more at higher speeds and also when changing lanes.  It just sort of feels slippery or something.  Not a major, black ice sort of fishtail, but enough to make me want to fix it!  Any suggestions? 

If you weren't pulling a LQ trailer, I would say that the trailer has too much weight on the back. However with the only change being the tires and having no previous bad experiences, I too, would assume the tires are to blame.

I would jack the truck's rear axle and while slowly spinning each tire, check the run out of each. You may have a tire with an off set belt, that while it looks good statically, may in fact wobble (side to side) when it is rolling under a load. I've had a similar handling experience, when I broke a belt in the sidewall of a radial tire.

You might also check your rear shocks. Even if only one is worn or damaged, it will give you the handling problems you describe, when the load shifts from one side to the other while turning. A new tire will react faster to suspension changes than your old ones did, and you can notice a difference in handling.

You probably already have checked the air pressures, but don't take it for granted that the tire store aired the proper tire inflations for your circumstances.

If everything checks out, about the only other consideration is the difference in tires between the front and rear axles. On some vehicles, a different brand, or even a different model of the same brand tire, will adversly affect a vehicle's handling. You may have to replace the front tires with the same type as were placed on the rear.

BOL Gard

Goodyear Wrangler AT/D2

Sold only at ....Sam's Club and Tirerack.com?  Load range "C"?  Are they Passenger or Light Truck? It comes in one size.

That 250 truck should have load range "E" tires on it. If you put "C"'s on the rear, then it's going to sway!

Is this your tire??

Now that the tires are in front, the problem has gone away.  I WOULD NOT recommend these tires for a truck that is going to be used to pull any kind of trailer!!  Now, what to do. . . I won't be able to rotate the tires with those in front.  I hope Sam's will take them back.  Any suggestions on tire to replace them?  The others are Firestone Steeltex Radial R4S.

Are they Wrangler LT's or Wrangler AT/D2's? Are you and fireflyer743 talking about the same truck/tire?

(quote) The others are Firestone Steeltex Radial R4S.

  Is this what's on the back now? Are they load range E? Are the new Goodyear Wranglers, load range E?..... If not make them take them back and put a set of load range E's on there to match the Firestones. Look inside your door panel and read what was installed on the truck when it was now. Then take the truck to your "SAM's CLUB" and show the %^$#%&^ a$$'s what the should have put on the truck..... If they're not 10 ply, load range E!!!

Is this your new tire... Wrangler AT/S 

Other Sidewall Style Options Blackwall Raised Black Letters

OR, is it this one... Wrangler TD

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Yes, Fireflyer did my tires - I didn't know that he had a "handle" on this page - surprised me!  But, same tires, same truck.  I'll go double check the exact tire, but he seems to think they are the E rated tires.  Whatever they are, I don't like them!  Now to find the receipt. . .