(http://i941.photobucket.com/albums/ad256/waldoegray/tank.jpg)
The 33 ton Sherman tank sporting a 75 mm gun was at a huge disadvantage in World War II compared to the German tiger tanks, the biggest of which ran 70 tons with an 88mm gun. The US, however, maintained an advantage in sheer numbers of tanks on the battlefield.
But the US was working on a 95 ton dual tread T-28 behemoth with a 105 mm gun to counter the massive German tanks. However, the war ended as the first two prototypes were in a testing phase.
No subsequent US tank has ever approached the T-28 in sheer weight although the 70 ton M-1 Abrams tank has a larger 120 mm gun.