Originally posted by GRUNHERZ
JS2 actually had much better armor than Tiger 1.
The direct comparison of armor thickness does not accurately represent the level of protection. The Tiger was armored with tempered face-hardened Krupp KC armor, while the JS2 had only homogenous cast-steel armor. Also the armor gun mantlet of the Tiger was 120mm thick and covered nearly the entire front of the turret (see picture below). On the other hand the JS2 had more sloped armor which would increase it's effectiveness ... but not as much as some would like to believe.
Armor Data
MODEL: TIGER I / TIGER II Nr. 1 to 47 / TIGER II Nr. 48 to end
FRONT
Gun Mantlet: 120mm @ 0° / - / Topfblende
Turret: 100mm @ 10° / 100 mm Curved / 180mm @ 10°
Superstructure: 100mm @ 9° / 150mm @ 50° / 150mm @ 50°
Hull: 100mm @ 25° / 100mm @ 50° / 100mm @ 50°
SIDE
Turret: 80mm @ 0° / 80mm @ 30° / 80mm @ 21°
Superstructure: 80mm @ 0° / 80mm @ 25° 80mm @ 25°
Hull: 60mm @ 0° / 80mm @ 0° / 80mm @ 0°
REAR
Turret: 80mm @ 0° / 80mm @ 30° / 80mm @ 20°
Hull: 80mm @ 9° / 80mm @ 30° / 80mm @ 30°
Germany's Tiger Tanks, Tiger I and II Combat Tactics, by Thomas L Jentz