The heavier the counterweight the less stress on the steering\front end. The tractor will spec out what the 3PTH capacity is. I would not go less than 250 lbs. I use 200 lbs on my 12hp B4200 (1,000 lb tractor) for a loader that lifts 400 lbs. Not having power steering, you can feel the difference the counter weight makes. I use about 500 lbs on my B3200.