The Russian Lebedenko tank prototype of 1915, also known as the Tsar Tank

found on http://steampunkvehicles.tumblr.com/

read about it http://www.landships.freeservers.com/lebedenko_info.htm

The upper cannon turret reached a height of nearly 26 ft. 

The hull was 39 ft wide with two more cannon in sponsons. 

Additional weapons were also planned under the belly. 

Each wheel was powered by a 240 horsepower Maybach engine. Each engine drove a car wheel which transferred power to a matching giant wheel by being pressed against its rim. 

The design had a top speed of 10 miles per hour