How do I measure my road bike tire for my wireless distance computer?

My bike tire is 23-622 700x230 and the cateye manual says its 2096 mm. I'm not quite sure if im doing it rite but when I measure the tire by doing a full rotation and measuring the floor at the starting and ending point I get 83.5in which is 2121mm. How should I go about doing this to get the... show more My bike tire is 23-622 700x230 and the cateye manual says its 2096 mm.

I'm not quite sure if im doing it rite but when I measure the tire by doing a full rotation and measuring the floor at the starting and ending point I get 83.5in which is 2121mm.

How should I go about doing this to get the closest measurement. And how can I tell if my bike is reading close to the correct distance travled?
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