I have been helping with the mowing at a local golf course and can tell you I have a whole new respect for people that mow on steep slopes. I have been using a John Deere HST in 4x4 with the fattest rear tires I have ever seen. I swore it felt like it was going to tip, but they said it would slide first. Slid it did for more feet than I like. They "control slide" down some slopes and just said "You'll get used to it." Their other mower is a Toro 4500D in 4x4 and is a beast. It's a five gang mower that I think would stick to an 89 degree slope. When I dream about mowers at night, the Toro is the one. They told me the Toro was a $65,000 mower. I believe them and probably should pay them to cut with it. They also have greens mowers that are reel mowers. They run the blades backwards and use a lapping compound to sharpen them until they will slice off regular paper folded once, and then they set the cutting depth with a dial indicator. Interesting couple of weeks. Be careful. Gerard