The wheels were NOT an ordering error. Rail World is forcing the MMA into the 1990's by installing 42" wheels as compared to the standard 40" wheels. This is what they did with the GE units they sent to Estonia.
Those Estonian GE's put on a large number of kilometers over the past four years---most likely they see about four times the monthly use as compared to MMA due to train frequency and speed differences. After more than four years, the Estonia GE units are just now in need of new wheels.
By using 42" wheels, the life of the wheel is longer than that of the 40" wheel. This means the wheels are on the axle for a longer time, which means you don't have to dismount and remount wheels as often, which means the axle wheel seats do not wear out as much which means you save MONEY!
Also, wheel diameter has nothing to do with any impacts or lack of impacts on jointed rail (Remember, massive steam locomotives like the Big Boys ran on jointed rail!!). Jointed rail get battered when the joints loose there support due to poor tie and or road bed conditions.
