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As big as BigBoy was, his drivers were equally as large. They were 68" in diameter!

BigBoy's wheel arrangement was 4-8-8-4. Now according to the Whyte System of Wheel Arrangements, the 4 represents the leading truck (4 wheels), the first 8 represents the first set of driving wheels (8 wheels), the second 8 represents the second set of driving wheels (8 wheels) and the last 4 represents the trailing truck (4 wheels). This adds up to a total of 16 drivers.

BigBoy had a total of 67,500lbs on each driver!

Total Weight on drivers: 540,000 lb (245 t)
Axel Loading: 67,500 lbs per axel
Driving wheel diameter: 68 inch (1.7 m)