I have a TC33D with R4 Tires. Tires are filled with CaCl. I pull a Woods GB72 box blade (72", 572 lbs) with good results. It would not work quite as well without the filled tires (or perhaps wheel weights)... remember, when you are actually using the box blade, it ceases to be rear ballast since the ground is supporting its weight.
I've used it to maintain 1300 ft of gravel driveway/road, leveled ruts in some old abandoned logging roads, and done some work to regrade around a new house we're having built. The gravel driveway doesn't even put a strain on it power- or traction-wise. In other situations, I have slipped the wheels on occasion, but it usually turned out to be a HUGE stone or large root I was hung up on. In wetter or muddy areas I sometimes lose traction, but I generally just don't take quite as deep a bite in those conditions and get through OK.
John Mc