Tires: no subject, bias ply tires, trailer tires

Question
We currently use ST22575 R 15 E range (10 ply) tires on our trailer.  Both Denman and Carlisle, the two main manufacturers for these tires advertise these as "trailer use."  Recently, we have been told by several trailer dealers that these are truck tires, not trailer tires, and that we should be using "D" tires on our trailer.  What's the difference between the two.

Thanks

Answer
Neesa,

You should not listen to those dealers that told you that.  They are wrong.

ST stands for "Special Trailer".  Besides, why would a trailer manufacturer put incorrect tires on their vehicle?  Wouldn't that open them up to a HUGE lawsuit?

The "D" tires are bias ply tires - old technology.  Many folks don't like radials because they claim the radials allow more "sway".  I think the real source of the problem is alignment and I will admit that bias tires are less sensitive in this area.

Another area where radials are claimed to be a problem is tread separations.  This is also true, but a lot of this problem can be traced to marginal or overloaded tires - and this would be a problem for bias ply tires as well, but the net result would be less destructive, hence the prejudice.  

Trailer manufacturers are lagging behind when it comes to selecting tire sizes.  All the SUV and pickup truck manufacturers have gone to larger capacity tires as a result of recent events, and this is proving to be of value.  Trailer manufacturers need to do the same thing.