I had the exact opposite results with M/T ET Street Radials compared to the M/T ET Street bias ply tires of the same size tires on the same size rims, I've knock the radials loose more than once at 55+ MPH passing without downshifting when the six pack outer carbs came open, not so with the ET street Bias ply tires, ever
I would run 18 to 20 lbs. n the radials and the same pressure in the bias plys unless I was going to race it and I would run them at 10 to 12 lbs. then.