Anyone who thinks tires will save them is completely idiotic. Think about it this way; the only thing that electricity cares about is the insulation it has to jump across. That inch of rubber actually is LESS insulation than the inch of air over your head. It doesn't matter if it's under you, you're still providing a path to ground. It wouldn't matter if you were standing on top of a 10 foot pile of rubber.

Contrary to popular belief, the reason it's safe to be in a car in a lightning storm has NOTHING to do with the tires - in fact most car tires conduct electricity. It's because you're inside a metal box, otherwise known as a Faraday cage (OK, a bad one due to the windows, but still...), which conducts the electricity away from the occupants.

Also, getting under a tree is about the WORST thing you can do. You're much better off standing in the middle of a field than under a tree. That tree is more likely to get hit by lightning than you are, and if it does, the lighting can arc from the branches or trunk to you, or it can even come up through the ground, up one leg and out the other, giving you enough of a kick to hurt you. I've seen several cases on TV where people under trees were killed.

The tree can also explode due to the sap inside flash boiling. If that happens, you're standing next to a bomb with pointy wood shrapnel.

Personally I ride through thunderstorms, but the thunderstorms we get in Michigan are puny things compared to what Florida gets.