Rubber tires work to reduce the damage done by lightning because the increase the overall resistance of the vehicle, and thus decreases the amount of current (which is what kills you in a lightning strike) flowing through the vehicle. The same principle applies to wearing rubber shoes if hit by lightning.

However, even without rubber tires the guys inside the tank should be safe from electrocution because the body of the tank effectively acts as a Faraday cage: When electricity flows through a large conductor, it will naturally flow only through the outer surface of the object. You can even be touching the inner surface and still be unharmed. In fact I believe people who work on high voltage power lines wear protective gear which works off this principle: Basically a suit of silver chain mail, which will conduct current over the surface and leave the wearer unharmed.

Regarding novel anti-tank weapons, surely the classic poor man's homemade anti-tank weapon, the Molotov cocktail has to be worth a mention? And the Soviet anti tank dogs sound great; can't understand why this unit has never made an appearance in any of the Red Alert games.