Who would win a fight tiger or bear?

That really depends on the sex, age, species and health of either species.

It should be noted that WCS/WWF scientists have disregarded as unreliable a lot of the historical data weights on wild Amur tiger that put in the 300 + kg range. Recent WCS data show weights for male Amur tigers under 500 lbs. The Amur tiger is not stupid when confronting bears. The male Amur tiger will predate smaller Asiatic black bears and sub adult and female brown bears. According to telemetry data on tigers from 1992-2003, around half the attacks on brown bears occur during hibernation but no males were killed despite their vulnerable state of hibernation. This finding is consistent with the historical literature & record. According to former Russian biologist S.P. Kucherenko & early Naturalist N.A. Baikov tigers will only attack bears of similar or smaller size which translates to female and sub adult bears not the larger male brown bear. There has been no record of male brown bears killed by tigers but there are records of male Amur tigers killed by brown bears & some of them were cannibalized. According to Russian biologists I.V. Seryodkin, N.A. Raikov, & Park Manager G.F. Gorokhov, adult Usurri female brown bear are not easy prey for dominant male Amur tigers - some of the larger female brown bears have inflicted severe injury to the victorious but bloodied tiger.
The fight between a tiger and a bear would be an epic one. The tiger would no doubt emerge victorious.