I have a similar problem on my place (section about 1/3 mile long @ 20% grade). I have an erosion problem too, though (see <A target="_blank" HREF=http://www.tractorbynet.com/cgi-bin/compact/showflat.pl?Cat=&Board=buildit&Number=125236&page=0&view=collapsed&sb=5&o=&fpart=>Sheeps Foot Roller</A>).
I've generally gone up the hill in reverse most of the time. I think I could go up "forwards" OK, but until I'm a little more comfortable with my machine and I get the ruts smoothed out, I figured this was the safest based on the suggestions I've read here.
I also have my tires set to the next to widest position - like the commercial says "Wider is Better". I still can get to just about every place I need to and it is amazing how much more stable you feel after adding a few inches to the width to the machine.
Ag tires - yea, go those too. I've been real happy with mine, and I think that most (perhaps not all) people here will agree that nothing beats an Ag tire for pure traction, which for my purposes (no nice lawns or "worksite") was a good fit. If you have a manicured lawn you want to mow though, Ag tires will tear it up without a doubt.
Weights - Haven't added any yet, but I plan on filling the tires when I get a chance. It should add considerably to both the stability and the traction.
Check out this thread as well - it appears to be suited to you!
<A target="_blank" HREF=http://www.tractorbynet.com/cgi-bin/compact/showflat.pl?Cat=&Board=custom&Number=125072&page=&view=&sb=&o=&vc=1>Riggin' for steep slopes</A>
Hope this helps! /w3tcompact/icons/smile.gif
