Most of the people on my RV forum have moved away from ST tires to LT tires. They claim these tires have a higher reserve load capacity, better construction and much lower failure rate. The failure rate of ST tires appears to be substantially higher. My tire guy says if I get pulled over by traffic enforcement I will be fined for illegal tires. Have you heard of this?
I have no experience using special trailer tires that I know of, but they appear to be the best choice for trailers according to my research. Radial ply tires for trailers used regularly and for long distances and bias ply tires for the utility trailer that you only use on the odd weekend. They carry more load than a comparably sized passenger or light truck tire too.
The biggest plus for these tires appears to be stiff sidewalls that cut down on trailer sway and reduce the chance of a blowout. They will also track straighter.
If you keep special trailer tires (or any other tire for that matter) properly inflated and make sure that they are not overloaded, they should not fail at a higher than normal rate compared to other types of tires.
Finally, you won't run into trouble from the law if you use special trailer tires on your trailer in B.C. You will have difficulties if you install them on your car or truck though as they are not meant for use on passenger vehicles. Reference Links