the old bias ply tires would flat spot . the old truck bais ply tires would throw you out of your seat un-till they warmed up. the modern radial does not. the modern tire of today has an added component to cause breakdown/dry rot more rapidly in the sunlight .. the usual problems with trailer tires are that they sit in one spot for long periods and sun/weather usually affects the sidewalls causing dry rot and sidewall strength loss in a small section.[ tire covers] another biggie with trailer tires is overloading. running them at or near maximum load then, rolling hard thru- curves or bumps which can load one side of the trailer [although briefly] with the -total weight on just two of the tires. if there is any loss of strength in the pair of tires on that side . you will find it quickly.