

In 1941 mediums started to become majority, and from 1942 light tanks were removed and their chassis converted to SPGs, TDs and such. In 1940 majority were still lights, but mixed with mediums. The Germans first produced just light tanks, complemented by mediums from 1938. So in 1941 the SU must have lights, not mediums, in the game also. T-34 became operational (with a lot of teething problems) around October 1941 and replaced the lights as the main tank in 1942-43. When the Germans attacked, the SU still had mostly light tanks, plus some KV-heavies that were difficult opponents to the Germans. Red Army used some (not so succesful) early mediums and heavies during the Winter War against Finland 1939-40, but vast majority was light T-26, BT-7, armored cars and such.

The Soviet Union built at least 20.000 light tanks before the Germans attacked. IRL most tanks of all countries were light in 1939, with a few mediums and heavies, depending on the country.
