[DeltAlum]

Rubber is one of the best insulators, so, in theory, as long as the car isn't touching something else (a tree branch, etc.), the tires should insulate it and it should be reasonably safe. If it is touching something that will take electricity to ground, though, all bets are off. For instance, if a chain or the stand at the tongue of the trailer was touching, that creates the path to ground. Also, if either were close to touching, a strong current can bridge a small air gap. If there is a strong strike close by, there may be enough static to damage electrical equipment -- and possibly even people, I suppose. I've heard of people being injured in motor vehicles if they are touching a metal part of the car and have a foot on the ground. Generally, though, you don't hear of cars being struck or you would be strongly discouraged from ever driving during a lightening storm.

Understand that I'm not a lightning expert -- but know a fair amount about electricity.

I was once in a TV production truck which was "struck." It certainly did fun things to the equipment -- but I suspect that we were really close to a strike, as oppossed to actually being hit directly.

Any time lightning strikes a person, there is an entry and exit point and any internal organs in that path could be seriously burned, or otherwise affected, so again, I don't think it makes much difference if one or both feet are on the ground.