"george" wrote

I can tell you now.
Water.
Plain unadulterated H2O.
Why would you want Urea in the tyre tubes and not on the pasture ?????

I can tell you for a FACT that water is not the only thing used.

In areas where the land is rather... Uh, not level - g - it is very
important to keep the tractor right-side-up. That is not always easy, and
still go where you need to go.

The fluid in the tires is put in around 1/3 to 1/2 full. That keeps the
center of gravity lower, and the more weight you can get below the axles,
the better off you will be.

Urea may not be the answer, but I know there is some fluid that is
substantially heavier than water that is commonly used, at least in my neck
of the woods.
--
Jim in NC