I have a back yard with a 16 degree slope, maybe a touch steeper on the crest. I bought a standard mower from Lowes- a new JD D140, and eased it over the edge. I rode it down the hill, out of control, bouncing my way to the bottom. It would not hold the hill, as the tires were skidding, and the grass was very dry (I purposely waited until we had a dry spell). I returned it, and am considering a zero turn, like the Toro Timecutter 4235, which has a lower center of gravity. Am I nuts? I hired a guy to cut my lawn, and he used his Scag zero turn. Other than scalping, he had not much trouble with the slope. My lawn is about 3/4 acre, with lots of trees and other obstacles. Would knobby tires help? What about dual tires? Weights? Thanks.