I keep hearing people mentioning trailer tires of the radial and bias variety. What are the benefits and drawbacks to either type?
One of the issues is that bias ply tires often develope a 'flat' spot after sitting for a while, it normally goes away in the first mile or so but can be extremely annoying. Radials are often claimed to have a longer lifespan.
Those are the only advantages of the radial for trailers I know of, there are others that apply to vehicles, but they don't all apply to trailer use. on vehicles they have the same advantages, plus they'll provide a smoother ride all around and generally provide better traction.
In my opinion, stiffening the sidewall for trailer use reduces the advantages of using the radial in the first place.