You should always use the tire pressure that is recomended in your owners manual. Over inflating the tire results in possible tire failure and also reduces the amount of traction your tire gives. Tires need to have some flex to them to achieve maximum traction.
Recommendations are for sheeple.
If he's running on beach sand or AZ desert he might want to deflate to 5-8lbs. If he's running on hard clay or concrete he may want to inflate to a greater than recommended PSI.
I want a crown to my tires for two reasons, one is to ease up on the steering sector as my front tires are now twice as wide as stock tires. I also want to 'dig in' for traction, not 'float'.
You will not blow a 4-6 ply tractor tire at 30lbs.
I also suspect that running low or recommended PSIs in front tires with a loader is the cause of most tire roll-offs, that really does some damage.