There is not a thing in the world wrong with bias ply tires. In fact, the commercial farmers who haul tons of grain in trailers are going back to them. After about 3000 miles on the new Chinese made radials (doesn't matter the brand they ARE ALL BAD) that came on my 2012 Ever-Lite, I had two blow-outs. Both were properly maintained with a TSP temperature and pressure monitoring system. Always proper pressure, never a heat issue.
I replaced them with Goodyear HMG 2020's bias ply,made in Canada. It says on the sidewall they are made exclusively for U-Haul. It was the best tire decision I have ever made. They are tough, tough tires and the trailer handles sooooo much better on the interstate. Would never buy anything else for my TT.