Just another thought.
I now have my tires loaded (methanol(sp)). When I first got the machine, the rear tires were not loaded. While mowing my somewhat hilly yard, I was always spinning. The dealer told me that loading the tires would take care of a lot of that problem. So, I had them loaded and it did help out a LOT. So, in my case, the loaded tires actually help prevent damage to the turf. Generally, around here, the dealers will load your tires for free. At least they have twice for me. Other than dealing with the tires if you have a flat or want to take them off for some reason, I don't see any disadvantages to loaded tires. I thought the water may make the tires bounce more, but after riding both, I can't tell any difference. I think it may take a little more to move the tractor uphill in high range now though.
Calcium did rust them out eventually, but I don't think the water/methanol will nearly as fast. My tires took about 37 gals each. At 8lbs/gal (approx), that is 600 or so lbs. of FREE weight.
Just my 2 cents... Each to his own...