It's because firetrucks have 4 people and 8 wheels, and 4+8 = 12, and there are 12 inches in a foot, and Queen Elizabeth is a ruler, and she was also a ship, and ships sail the seas, and there are fish in the seas, and fish have fins, and the Finns fought the Russians, and Russians are red, so the firetrucks are always "russian" around.

*instantly thinks about Russia with a bloody metal pipe*

Russia: You called, da?
Me: HIIIIIIEEEEEEEEEE!!!!!