I wonder if you could use a small ATV tire.
Then order them online or ebay.
Otherwise, certain Walmarts sell ATV tires.

Never heard about filling the tires partially with water. Pretty interesting idea. Otherwise, maybe tire chains might be an option, or adding a few 30lb weighs over the trailer hitch area.

Our property is pretty much dead flat so speeding isnt a problem, although it cuts like shit in anything more than 2nd gear. But it's all fun

I want to get the plow attachment for the mower, but I dont want to remove the cutting deck in the winter.Not to mention that the plow, weights and tire chains cost $399+ from sears.

Maybe I'll mod something else to work for cheaper.