The Measuring Wheel kit consists of three main components, the wheel itself with the integrated rotation encoder, the heat resistant light barrier sensor to indicate the rotation of the item to be measured and the controller which calculates and displays the diameter. The wheel with the diameter of 176mm is running without slippage on the surface to be measured (e.g. support roller). During each wheel revolution 1760 electrical impulse are sent to the Wheel Controller which is counting them. With the help of a magnetic switch flag attached to the side face of the support roller or tire, the light barrier sensor provides each revolution an electrical impulse to the Wheel Controller. This revolution impulse starts the counting of the impulses coming from the wheel encoder. After one revolution of the support roller or tire, a new impulse from the barrier sensor is stopping the counting, the diameter value is displayed and immediately the next measuring cycle is started. With each revolution the diameter value is refreshed whereupon the last reading appears at the lowest of the three rows in the display. The second and the third row show the previous readings.