Tires: Tires for a 5 ft. X 12 ft. Utility Trailer., bias ply tires, radial tires

Question
I was told by a friend that he installed radial tires on his utility trailer and it started swaying at approximately 55 mph.  He replace the radials with nylon tires and the swaying stoped. Please give me some insight on this.

Thanks, Gene.

Answer
Gene,

There are probably 2 things that are going on here.

1)  Radial tires need to be inflated more than bias ply tires - usually 5 psi - for the same load capacity.  This additional pressure helps somewhat with direction stability.

2)  Radial tires are more sensitive to toe and less sensitive to camber than bias ply tires.  So if there is even the slightest bit of toe out or looseness in the suspension, bearings etc.,  a radial tire will be more likely to "hunt" back and forth trying to find a "neutral" and therefore stable position.  So a check to see if there is a bit of toe in is not a bad idea if a trailer shows some signs of "sway" with radial tires.

Hope this helps.