John Deere 4052R Cab,, Deere 855D UTV, Z920A Zero Turn Mower and assorted implements
You should have 15-19.5 tires on your B3200.
If that's the case, filling each tire should add about 29 gallons (if filled to ~75%).
How much weight depends on what you fill the tire with.......water weighs about 8.35 lbs per gallon, so that comes to about 250 lbs per tire.
There are also several charts on this subject type in tractor tire fluild filling on Google. there are more in depth charts. Roy is correct though about the weight given your tires..