Tiger I = 1942 design
IS2 is a 1944 design
Since we already have the Tiger II, I don't see why people are comparing it to the Tiger I (which is often beaten by even the panther).
Comparing apples to Oranges, The Tiger was the king of the battlefield before most tanks were even on the drawing board. When it was available there were no anti-tank guns designed yet to even knock it out at any range from the front. The Russians tried to find a situation to the Tiger problem, for example the Kv-85, Su-85, T-34/85 which were stop gaps while they were designing newer tanks/AT guns for the problem at hand even then it took over a year and a half.
Nothing can be compared to the Tiger (built in 42/ready for combat in 43) vs a Panther (built 43, bugs fixed it in mid44). Neither American, British or Russian had any options to combat it effectively, however everyone did come up with Viable options to defeat it (Firefly is a prime example).
Same mistake is made with comparing aircraft like a Me109 to a P51D, one plane built before 1939 and the other 1942/43 and both have quite different uses, but based on the same principle.
The same thing has been going on for many years now, the Russians built the Mig-25 and the Americans responded with the F-15 Eagle, both can't be compared as the Mig-25 was designed as a High alt, Bomber interceptor and the F-15 a Air superiority fighter.
Apples 'n Oranges
