Fluid is the norm here.
Cast iron wheel weights are very common.
I would imagine it's the same there.
I found it weird when Barry commented negatively on extra weight.
I get it, weight will sink him. Different conditions, different solutions.
Yeah, this sandy country down here will ruin your day if you are too heavy.
About 4 years ago, I had my big shredder go down to bottom in a pasture. Couldn't do anything with it. Luckily, it was my last ranch to shred of the year.
Had to unhook from it and wait for conditions to dry out. My tractor had enough float, I didn't get it stuck, but it was still iffy...
That shredder stayed in the pasture for about 4 months IIRC.
Now I have this Bad Boy...
Gotta be real careful to not stick it too.