I played Gog Magog and watched how many T34 attacked. Soviet tanks have all radios in the game, nearby are AT positions. I know the weather conditions were optimal in that game. The T34's all shared C2 by radio so if one tank spots inside the minute tentative contacts are shared. Also, the size of a King Tiger tank makes it easy to spot. Numbers in the game make a huge difference. In another Red Thunder scenario we spot Tigers in a hull down weather hazy distance over a kilometer. The German armor was spotted by infantry and the tentative contacts relayed by runners to the IS2's. The IS2's independently didn't spot anything it was combined infantry with the armor which make them spot first.