After reading all this excellent dialog, I feel I must be living on borrowed time... I dutifully watch my tiltmeter on both my tractors. On my
L5450, I agree 15 degrees is scary and prudence prevails. However, on my
B7200 with MMM I regularly mow at 20, and often hit 25, and occasionally touch even beyond that point. I've been using the little tractor for these slope applications since 1985, with nary (knock on wood) a wheel lift. I guess my point is, as others have stated, that many hours in the seat and "tractor zen" alter permissible slopes.
As so many have stated, specific conditions mean so much. A few years ago, while operating my
L3350 on about a 12 slope, with tree planter behind it (engaged), I had just hit a slight dip on the side slope when I heard some awful screaming from my partner in the tree planter. Stopping to see what the issue was, he feverishly pointed to my uphill rear tire which was about TWO FEET off the ground. Literally, the only thing holding the tractor upright was the coulter and planting shoe, which engage the soil by about 26"... they in essence were acting like a sailboat's keel. We stopped, assessed the situation, at which point I decided that I would sacrifice the planter by leaving it engaged in the soil, turn the tractor downhill, and thus probably bend the daylights out of the planter or even three point lower links. End of story: I'm still alive, the tractor safely came back to terra ferma, the tree planter is a good sport and didn't bend to pieces. Lesson: We now DO NOT plant on any slope >10 for any reason whatsoever. btw, the pucker factor, which normally kicks in for me at sissy slope levels (on the old
L3350 or
L5450 that is), never kicked in with the tree planting episode... proof positive that tilt meters are truly effective tools that save lives, and that tractor zen is good, but not adequate in all situations.
Last preachy tale: Last year, my neighbor who farms over 3000 acres tipped his little (MF135) bush hog tractor over and was severly injured. No ROPS or seatbelt!! He tipped the tractor over on a slope that both his father and his grandfather had mowed their entire lives!! He is 61 years old, and no novice. I don't know if a tilt-meter would have prevented this event, but would certainly have been the cheapest insurance premium available. Everything must have been "just wrong" for the catasrophe to occur. With broken ribs, pelvis and lots more, he was bed-ridden for several months, plus tons of physical therapy. He now hobbles pretty danged good. Just think of how many tilt meters could have been purchased for his opportunity cost and/or his therapy and medical costs.