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

  • frank@sopuli.xyz
    1·
    22 days ago

    Hi! I was a controls engineering in the automotive industry in the US for a while.

    Yup. You sure should! Some cars even have tire dimensions and quick selections of winter/summer tires for exactly that. Some cars make it much harder/impossible to do.

    Same with motorcycles if you swap sprockets of course (a common modification)

    Edit: seems bikes are a pretty mixed bag where the speed sensor is. Your mileage (and speed) may vary there