Most we ever did in one day was 1200 bales. I think we started around 10AM. It was a rare dry day in the morning.. Chores before and after made for a long day.
Pucker x2...the first time you're going too fast on the pavement and experience viewing the "death wobble" in your truck's rear view mirror.
I would suggest looking for used airplane tires. They sell them in the size you mentioned for agricultural use, used. They will 16 ply or even greater.