75% fill of tire with fluid, not 100% not 50% but 75%.
100% fill with fluid = tire never gives, and one good bounce of tractor, and tire could rupture,
50% full of fluid, and the fluid is just waving back and forth inside the tire. if you were on a hill and all of a sudden wave of fluid would down hill. guess were you might end up? bottom of the hill...
75%, puts fluid right at the the valve stem. when position the valve stem at 12 o'clock, and filling / burping air / filling with fluid / burping air. it keeps enough air in the tire. so it smooths out the ride, (the tire gives and takes some), and it helps keeps the waves being formed within the tire to a certain degree, it also keeps the entire rim completely under fluid, to help avoid possible chance of rim rusting.
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i have had enough flats, i don't want to mess around with breaking beads on tires, and dealing with fluid gushing out of the tire. or beads not seating properly. i simply don't want to mess with it.
it is easy enough to fill a tire with fluid via the valve stem. gemplars, sells a tire valve stem fluid thing, that connects to tire valve stem, a hose from pump, and a second hose coming off of it, so you can burp air out. all through a single simply valve.
if ya don't have the special fitting, even then it is easier to deal with filling tire with fluid in my opinion. i don't like dealing with a few hundred pound fluid filled tires. let alone 100 plus lbs tire than is not even on a rim. KISS (keep it simply stupid)
ya not filling / unfilling rear tires daily, weekly, monthly, only time ya really mess with them, is when ya initially get a new tire, and/or if you have to deal with a leak (thorn, or like) in tire.