Any ideas on how to adjust the speedo for aftermarket wheels and tires?

Could I just punch it in throught the ecu or will it be something like soldering in some reisistor or something to the tranny speed sensor?

 

I didn't know you could. All the posts I've ever read about aftermarket wheels
just tell you how much you can expect your speedo to be off.

 

yeah, unless you radically change your wheel height you're not going to need to worry about it. I think www.tirerack.com has a calculator to tell you what to expect with your new size

 

I know its some 6% off bit I strive for accuracy. Esp becuase I intend to use my obdII reader for recording the speed, and other things.

 

When I swtiched from 195/50 stockers to 205/45, it translated into about 2mph faster than actual at about 55-60 mph.