At the risk of going way off topic according to Wikipedia, the tri-star wheel configuration was developed in the United States around 1967, by a couple of Lockheed Aircraft Corporation engineers. That said, an 8-wheel baby carriage was proposed by a Czech gentleman seemingly living in England as early as 1948-49. The configuration of the 6 wheels at the rear kept the carriage horizontal in all circumstances, whether going up a flight of steps or coming down a hill.