I have been using a 36" Snapper BD with sulky (1 wheel) 12.5 HP Kawasaki, for 2 years and have had no problem on flat ground, uphill, or downhill. In Feb. this year I was weighing in a about 290. I'm down to 255 now so not only do I feel better, I think my mower does too! I also have a 48" Ferris SD with 14 Kawasaki and haven't had any problems with it pulling me. On the Ferris, I had to put weights on the front to keep from doing wheelies, but that was because of the engine position ( most of the engine weight is behind the rear wheels) not beacuse of my weight. I know most on here don't think much of the Snapper mowers, but mine has been trouble free and has a great cut. The Ferris also has a great cut, but it really shines (cutwise) if I walk instead of ride. I use it without the velke alot....this is why I've lost 35-40 lbs. in the last 4 months.