spedometer question

[i885744]

Is there any way to recalibrate the spedometer on a 1992 e36 325i 4 door automatic? I would like to switch from the stock 205/60 r-15's to a 225/50-r15 but i know for a fact that they are different heights and would require spedometer correction. I know on some cars the dealer can repgrogram the spedo using the computer, other cars require changing of the spedometer cable gear. Have any of you done this tire swap? Thanks for your help, Mike Cook

[dutchbmw]

Do you really mean 225/50-15 or should it be 225/50-16?

[dutchbmw]

P.s. to the BMW-forums!

[Eggrolled211]

60 series tires to 50 series tires...less side wall thingy huh?

[007ben]

Will the total diamter of of the tire change? if you get shorter side walls and wider rims and stay at the same outside diamert,radious, etc... you will be fine.

That almost made sence I think.

[El Presidente]

no, you didn't. good try though. the speedo goes by the rolling diameter. If you increase/decrease the sidewall, increasing/decreasint the width wont offset the change. What I think you meant to say was if the height of the rims instead of the width.

At any rate, I think the speedo can reprogrammed but I am not sure how. On OBDII there is a computer than can be plugged in to change it, but I don't know about OBDI.