i read a brown bear is dinner to siberian tiger. i read many articles on it but never heard a brown bear killing a siberian tiger. brown bears run away from siberian tigers. even in india bengal tigers(smaller than siberian tiger) kill black bears. read more
If you put up a fight between Siberian Tiger and grizzly Bear, then I'm not sure that Tiger wins. Because Siberian Tigers are bigger but docile as compared to Bengal Tigers. I saw in many fighting videos Siberian Tigers giving up to Bengal Tigers or even African lions in some cases. read more