Not to resurrect an eight year old thread but for reference, I have had no problems running my tires filled with water and anti-freeze on a 2014 M59 now for about 2 years (~250 hours of use). One thing I have found are my tires aging quite quickly mostly fronts (unfilled) and getting cut-up in the rears; perhaps due to the extra weight or being stored outside in the dry Colorado air. I do store mine under cover though; Walmart's XL RV tire covers fit the fronts great and I hang canvas tarps over the rears.
I have found that the extra rear weight is essential with an M59 for some of my work. I have been clearing rocky land with a heavy grapple and a light rear ripper bar being the only implement out back often on steep sidehills and carrying cut trees on my land going down those steep hills. Still no issue lifting the back with the stabilizers even when filled.
No problem with the stabilizers:
Certainly helps when moving sandstone ripped from the ground: