By "stability" I meant how well it tracks behind the towing vehicle and how little it gets thrown around when big vehicles pass it.

So you are saying that this is not necessarily specifically related to the width of the axle, but is also related to the length of the trailer tongue?

I'm not an engineer, so bear with me on this. If you have a narrow axle and your trailer wheels are close together, does that mean you should have a shorter tongue. And if you have a wide axle (wheels far apart), you need a longer tongue? Or is it vice versa?

I know I have followed some trailers with very wide axles, carrying ATV's, and they seem to be all over the place. And I have followed one of our trailers with the narrow axle carrying three boats, and it seems to track very true.

So is this all a function of relative tongue length vis-a-vis axle width? (Assuming proper weight on the hitch.)