OK well this is not a problem, there are charts that will tell you how much liquid goes in what size tire, unless somebody has it right at hand I ll look for it,,
1 jack the tractor up, both rear wheels off the ground maybe an inch or so,,,
2 turn the wheel so the valve stem to high 12. remove the valve stem guts
3 Now you can go to most any tractor store and buy the adapter for your garden hose that goes on the valve stem.
4. Now you can do this a lot of different ways,,,, once you figure out how much liquid goes inthe tire use an old pump type spreayer and remove the srpay end and put in one of thos needle valves inthe hose,, fill the pump up with how much anti freeze you need and pump it in,, Then fill wit water.
Check every so often by turning off the water hose and see if any water mix is coming out of the valve stem when it does you have it filled ( that way there is an air space in the tire which will soften the tire and easy the abuse on the tractor and you)
5 Put the valve guy back in and pump the tire up to the stated pressure on the tire,, and Your good to go,, then do the same thing to the other side,,,,
ONE WORD OF CAUTION,, don't take the tire and wheel off and fill it, do it on the tractor,, those wheels are heavy enough all by them selves,, fill them with water and you will bust a gut getting it back on,,,, dont ask