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
I have a vivid memory of staying home sick from school and watching daytime educational programming on PBS. There was a (dry, low-budget, old) math show for kids on. They had a “skit” where a couple of teenagers went and got replacement tires for their car. They came in with a set of numbers that I assume had to do with the tire measurements. (Maybe hub diameter, hub thickness, and tire outer diameter.) They found tires that matched on two of those numbers, but the guy was impatient and said it had to be basically the same because it matched on two parameters. Then in the next scene, the same teens were driving the car with brand new tires and they got pulled over for speeding. The driver was sure the speedometer said he wasn’t speeding, but the new outer tire diameter changed the calculation, meaning the speedometer read lower than they were actually going.
This is the first time in my life the memory of that show has ever come in handy.
I remember that show! Not that episode specifically.
If it’s the one I’m thinking of, it was called Square One.
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
People who put lift kits and huge tires on a truck they’re using to drive around town don’t really use the kind of critical thinking to worry about that. They’re mostly thinking about their credit card payment and how it’s all brown people’s fault.
I hope you atleast see the irony in suggesting people are racist based on the kind of vehicle they drive.
Judging people for their actions/choices is nowhere near the same as judging someone for how they were born.
Concluding that someone is a lesser human because of their skin color seems just as illogical to me as calling someone a racist because they drive a lifted truck. These things are completely unrelated.
