How is the speed of a car measured by the odometer? Surely it has to use the circumference of a tire in some way, and does that difference in circumference due to wear affect the correct measurement?
Answer
Dear Christopher,
the speed is measured by converting the speed of rotation of the axle, taking into account the diameter of the wheels. Wear does indeed have an influence, just like the temperature and how hard your tires are inflated. That’s why most car manufacturers set the pointer a bit higher by default: You will (usually) drive slower than what the meter shows. And that is why you always have to use the same type of tires (or at least with the same outer diameter).
Answered by
ir. Bart De Schouwer
For my position I am in charge of a group of engineers who maintain production equipment. It is mainly with my ready knowledge (education, interests, …) that I could answer questions.
Kapeldreef 75 3001 Leuven
http://www.imec-int.com
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