Ralph, although not necessarily very sanitary, a quick little touch of the liquid to the tongue will tell you if it's calcium-chloride filling from the tires or condensation. Chloride is VERY salty. Also, as others have said, it it's not doing it now, and the tire's back in the same position, it likely was condensation. I've never seen it that significant though and yes, you probably should have seen some evidence of it under the tractor also as there plenty of mass (and liquid in the form of transmission fluid) in the tractor. Let us know what you find.