50/50 mix would be good to -34F. Do you need that much protection. For tires a little slush doesnt hurt a thing in tires. I would think that a 30% antifreeze solution would be plenty for tires.
You can look up the freezing point of different ratios on internet (lots of sites) and decide what you need to do. A device to fit on the garden hose to put in water is about $12 at NAPA maybe less at TSC.
One TBN poster described the easiest way to get antifreeze in the the tires is to put tractor on jack, lower the jack to flatten the tire slightly then with the tire filling gadget on the tire and end of hose in antifreeze bottle, jack the tractor up and the fluid will be drawn into the tire by vacuum. Repeat as needed to get all the antifreeze into the tire. Have the valve stem at top dead center for all filling. When you stop getting air out and water comes out instead, the tire is full. You will have to stop filling with water and bleed the air a few times to avoid overpressuring the tire when filling. I filled my Yanmar tires when I got it several year ago in about 5 minutes per tire after getting the blocks in place for the jacks that it. Total time was about an hour for all of it including swapping the tires from each side to widen the stance prior to filling with ballast. I did have a helper on this as I didnt want the tires to get away and lining up the lug bolts was much easier with a helper.
Check your pricing for the required amount of antifreeze and you can readily see how much your dealer is charging for labor. I wouldnt think more than 4 gallons per tire is required @ $10 or less per gallon.