I've had three ATV's over the past 20 years. Wheelied over the 1st one on a hill due to improper tire inflation (over inflated) and giving it too much gas.
I'm pretty certain manf. stopped making the 3 wheelers due to injuries and lawsuits. Remember when they were constantly in the news?
I will say the 6 wheeler (Polaris) was stable on hill inclines. The chain drive on them lets the tires and suspension hug the terrain instead of losing contact with one wheel as the shaft drive ATV's do. Plus Polaris had a tracker system on the 6x6 which gave tremendous ground contact and made it even more stable on inclines.
Attached photo shows me hauling out my ice shelter. It was able to go places my other ATV's could not. It just felt so much safer. I noticed it right away after the trade in.
Sigh....
This lake usually has a plowed road out to the village but the plows had to give it up one year. I climbed over their barracade without a hint of feeling tippy (this is my 2nd load out).The trail behind me is mine and the boys had to use it to walk out.
Anyway I do feel a 6 wheeler is alot more stable than a 4 wheeler which is alot more stable than a 3 wheeler. And I am going back to the 6 wheeler for that reason with the next trade in.