Note to military vehicle designers: "Sunroof" equals "grenade magnet."
Due to the lack of a roof, the BTR-60 could be taken out by even the simplest of explosives. Take a grenade and throw it at any other armored vehicle -- it just bounces off the side and explodes as the armor protects the crew. Now throw one at the BTR-60 -- it goes in the giant gaping hole at the top and explodes directly in the troop compartment, killing absolutely everyone. All that armor does little good when the explosion is happening on the inside, and in fact just helps keep all of that killing energy trapped inside where the people are.
It's not like they couldn't put a top on it; the Red Army even requested one. But the designers basically said, "Screw you guys," or, to be more precise, they argued, "The limitation of losses wasn't the emphasis." Oh, well good. Glad we got that settled.
"Your lives are less valuable than stirring propaganda photos."
Their solution? Cover it with a tarp. Explosions and bullets rip right through it, but at least it kept the soldiers out of the rain.