To check how evenly filled you got your tires, jack up the rear of the tractor.
Position the valve stem at 12 O'clock.
Remove the valve core.
Slowly rotate the tire until fluid comes out. Normally, most people fill their tires to the 10 or 11 O'clock position which is about 75%.
If both sides are even you should have fluid come out at the same clock setting. If one is at 9 and one at 10, add more fluid to the 9 side.
When complete, reinstall the cores at the 12 position and add air. Most people run between 12-20 PSI.