Welllll I used old used antifreeze I found at a auto scrap yard. Yeah I know its not safe for the birds and bugs what ever, Or use windshield washer fluid its pretty cheap and I think is a tad over 8 pounds a gallon. I will here state, that what ever you use the easy and best way is to jack the tractor up making sure to block the front wheels. You dont need to jack it up high just enough to take the weight off the tire. Pull the valve gut out and let it deplete it self of pressure. Now there are several ways of filling you can go buy an adapter at TS or RK for like 20 bucks or you can red neck it. I used an old pump sprayer removed the nozzle and just forced the hose over the vale body, like I said red neck. then pumped inthe fluid. You will have to let out the air once in a while because as you fill the tire/tube the ambient air will begin to compress to the point you cant put any thing in, so you let it out and start filling again. Some guys like to keep the valve stem at 3 or 9 o:clock and just fill to that point, about half a tire full. Myself I set it at 12 o:clock, now if you go that route when you think it is full, remove the hose and it will squirt out untill the fluid level is level with the valve. At this juncture replace the valve stem and pump the tire up to the pressure stated on the side wall. You will still have the air so its not like riding on a foam filled tire so its all good. DO NOT, take the wheel off to fill, unless you have some bulky help to put it back on! Don't ask
I hope some of my rambling helped you