Wheel Spin Indicator

["3 liter" <saltfever@comcast.net>]

Just remember when measuring the difference of rotation, the circumference
of both wheels must be the same otherwise a correction or scale factor has
to be built into the electronics.  Rarely are the front tires the same
diameter as the rear. This means you would have to measure the circumference
precisely of both and then enter a scale factor into your slip-indicator
before running.  -Elon