Complex sentence: Before Lego began manufacturing its own tires, it made "pre-molded mini cars" in the early 1950s, and users sometimes made their own, fashioning eight Lego blocks into a wheel.
Split into simpler sentences: Before Lego began manufacturing its own tires, it made "pre-molded mini cars" in the early 1950s. Some users chose to make their own tires, fashioning eight Lego blocks into a wheel.