The project was scrapped after initial tests deemed the vehicle to be underpowered and vulnerable to artillery fire.
It differed from modern tanks in that it didn't use caterpillar tracks—rather, it used a tricycle design. The two front spoked wheels were nearly 9 meters (27 feet) in diameter; the back wheel was smaller, only 1.5 meters (5 feet) high, triple wheel, to ensure maneuverability. The upper cannon turret reached nearly 8 meters high. The hull was 12 meters wide with two more cannons in the sponsons. Additional weapons were also planned under the belly. Each wheel was powered by a 250hp Sunbeam engine.
The huge wheels were intended to cross significant obstacles. However, due to miscalculations of the weight, the back wheel was prone to be stuck in soft ground and ditches, and the front wheels were sometimes insufficient to pull it out. This led to a fiasco of tests before the high commission in August 1915. The tank remained in the location where it was tested, some 60 kilometers from Moscow until 1923 when it was finally taken apart for scrap.
From: http://en.wikipedia.org/wiki/Tsar_Tank
