You can drain the fluid out of the wheels into buckets. Just get plastic tubing that fits tight over the valve stem and a valve core removal tool to remove the valve stem. Try to put the tractor above the bucket - you may get several bucket fills per wheel so need to have a place to store or dump it - large plastic garbage can will work to hold it. I dumped min on weeds. A year later the weeds are back.
You can take the wheel to a tire shop - google your are for places that deal with tractor tires or truck tires. Or you can check youtube how to remove it yourself - you want to have good long tire irons and it is a PIA but doable if you have a bit of muscle or leverage (And a friend).
Once the tires are off, check the rim for rust - brush loose rust off and use rust restorer to turn the remaining thin layer of rust black. May need a couple applications. Then use good metal paint.
While you may be able to go tubeless, I recommend using tubes once you have the wheels off. They cost a little bit but provide isolation of any fluid from the rim. You can have the wheel shop order inner tubes or get them online. WalMart sells them if you can't find them cheaper elsewhere.
You can re-use the Calcuim Chloride in tubes but the valve stems will corrode after a few years and start a slow leak you may not notice until the rim is rusted through. You have to watch for leaks and get the valve replace regularly or replace the inner tube. If the stuff leaks on your rim you could get significant corrosion. I got a 2 inch hole and very rusty rim. Yes, you can have it welded ... or buy a new rim like I did. 2 part rim so only $125 US for the .
After the 2nd rim in 25 years I decided to get rid of the CaCL and find other options, for now, nothing in the tires. My implements are heavy enough for my 8N and the old tractor is happier going up hill.
When you have the shop remount the tires on the rims (with inner tube?) don't have them fill it. Lots of youtube videos on how to fill the tire yourself... What works for your area depends on freezing points. In some areas tire shops will send someone to your place, but in urban areas that can be hard to find. You just have to have patience to do it yourself.
Not filling your tires can give a better ride if they are "just right" and absorb shock but metal weights can be expensive. You can get inventive and make your own balast to go on the 3 pt hitch.
Of course if you have a truck you can rent a trailer and take the tractor to the shop and have them do it all ... much easier.
