I remember the history of the old tiger and the leopard. It was posted by peter but unfortunately I didn't copy it.
Personally I found very difficult to believe in such an story, I could interpret the facts in a different way, like: the leopard hunted the prey and the tiger just steal it. To be sincere I don't remember the facts very much, so I am only speculating at this moment.
About the 40 y. tiger, I think it was Jim Corbett who describe this (or it was Pocock?), however it is really hard to believe in such accounts, specially in the old days when there were more tigers and more intra-specific competition.
At this day, the oldest Bengal tigers were the female Chuchchi of 15.5 years from Nepal and the famous B2 of 14 years old; both died from fight injures. As for the Amur tigers, the oldest female (Olga-Pt01) was poached when she was 12 years and the oldest male (Dale-Pt20) died at its 12 years drowned in a freezing pool. Definitely they could live much more, but the destiny act adversely.