Speedometer Options

[kerosene]

When you get a larget size rim and tire, you have to update your speedometer, how do you exactly do that? would a 4 wheel alligment do it?

[Kwanza26]

There are two main types of speed sensors. mechanical, and digital. The mechanical ones are turned by a toothed gear, which literally turns the speedo. The digital ones (like the 6th gen celicas) use a magnetic pickup to calculate analog movement to digital signals which then is calculated to actual speed by the ecu. Basically, the ONLY way to re-calibrate you speedo is to alter the digital output, ie: change the sensor, or alter the way the computer computes speed, ie: alter the computer.

Either way, speedos and the very nature of converting physical movement to digital calculations is NEVER accurate, so things will never be perfect. Not something you need to worry about, IMO.