Yesterday's tires on yesterday's rims were sufficient for yesterday's speeds on yesterday's roads. This is today.
[img]http://thumb11.webshots.net/t/64/464/6/3/64/2252603640096215731mOZawt_th.jpg[/img] You didn't mention if you had run those tires long enough to warm them up. Bias ply tires have a very defined operating temperature range, outside of which they are not at all happy. Also, Chinese tire manufacturers have not yet, in my opinion, progressed to the point that the purchase of their product is anything more than a crapshoot. Sorry. You might be one of the lucky ones.
On heavy trucks back in the 70's, we routinely ran bias on the steering with radials on the drives to achieve the longest wear, without any ill effect. I think, though, that there's a chance your truck could transmit vibrations through the frame to the tires at the other end when it is empty. I'd go with tubeless radials all 'round, as you can see.
