wheels are 1.25 inches in diameter.
 fastest speed is 3ft/sec.
 maximum distance to travel is 16 x (18 cm) 
 1. convert the dimensions for the wheel and maximum distance to feet.
 wheel diameter in feet: = 1.25/12 ft
 maximum distance in feet: 16*18 = 288 cm
 max d = 288/(2.54*12) = 24/2.54 ft