Saw a truck around town today with a ridiculous lift kit and chunky off-road tires that were clearly much larger than factory standard, and it got me thinking; if you install this kind of modification in a car, do you need to adjust the speedometer to compensate? What about the odometer?
My logic is the only absolute measurement the car has is how fast the wheels and drive shaft are turning, so presumably there is some sort of multiplier - 1 revolution = X meters - that is then used to show speed and track distance travelled, but that factor would need to change if the circumference of the tires did
Tangential speed of the tires is proportional to the angular speed, and the factor is the radius (assuming a perfect circle with negligible differences from tire deformation). Same thing with distance. Tires that have half the radius of stock would report speeds and distance twice as fast/far, and twice as large tires would be half as fast.