2" Clear Yellow Acrylic Disc Wheel - 2 Pack

X = Wheel Diameter
Y = Motor RPM

inches / second = XY(3.14159) / 60
feet / second = XY(3.14159) / 720
miles per hour (MPH) = XY(3.14159) / 1056

Example: X= 4” Wheel Diameter
Y = 20 RPM Motor

inches / second = 4 x 20 x 3.14159 / 60 = 4.19 in/sec
feet / second = 4 x 20 x 3.14159 / 720 = 0.35 ft/sec
miles per hour (MPH) = 4 x 20 x 3.14159 / 1056 = 0.238 MPH