Depends on how big the bale is. I think the smaller bales are about400lbs,but they up to 1200 lbs. 1/2 t should handle them if they fit in the bed though. Spring wise, you could always put the rubber donuts on the springs as helpers if it squats too much.
A 3'x 3'x8' bales weighs right at 800lbs if grass hay. So if you know the dimensions of the round bale, you could figure the weight pretty close using the volume.
