FYI - Found 12 x 5.30 6 ply trailer tires online at Walmart. Not the turf tires I was looking for but two tires with tubes shipped for less than $80 US, what a deal. They mounted just fine on the old rims. Was able to take the old tractor out for a short ride tonight after it sat in a field for past 8 to 10 years.
Just need to find a fuel tank cap, water temp switch (lamp stays on even when cold) and figure out the wiring for the Alt / voltage regulator ( connectors at voltage regulator damage with pins pulled out & cut off). The Alt. end for the Alt. field control plug is ok, just the voltage regulator wires are missed up (any tips are welcome).