Both of them.
20,000 - 25,000 lbs, depending on specifics.
Tandem by definition is two. So tandem axle is two axles. Example would be a tractor trailer having two axles next to each other is a tandem axle.
Five
They both are.
Tandem axles are connected by spring Multi axle trailers Shipyard Transporters
vkbvbp;.v;xcmvimv,
A tandem truck usually refers to the amount of axles on the trailer or tractor. A single drive axle on a tractor would be referred to as a single, or the same for one axle on the trailer. I have seen it referred to the amount of tires on the end of an axle. When there are two tires on the end of the axle, that would be referred to as a dual, not a tandem.
They both should.
60:40
You need to be more specific about the configuration. Is a single axle straight truck, a tandem axle straight truck, a tandem axle straight truck with additional lift axles, a tractor trailer...?
The exact same thing as the first drive axle.
As much as it's legally rated for. You could be talking about a truck in any configuration... single axle, tandem, tri-axle, quad axle, quint axle, centipede, superdump, etc., or a tractor-trailer, then you get into various configurations there, including heavy haulers. You need to be a little more specific.