Im looking into gettin a set of 18's for my o6 monte carlo 2lt, currently it has the stock 16 inch alloys (boooo) and want a serious upgrade. Will i have to reset my spedometer after i get the rims? Would the dealership be the only place to do this? Thank You

 

putting any bigger or smaller tires and wheels on your car will make your speedo wrong up to 5mph. dealer can do this but im sure any custom shop can as well

 

i have 18" tires on mine. but the tires and wheels are the same size as the 16" wheels that were on it.

Now with that said in reality it would not make to big of a diffrence on mine do to the tires and wheels being the same size as the 16" wheels with tires on them combo.

But you can get the dealr to reset it for you OR if you know anyone with a programmer that will work on your car you can get them to do it most have a settign for larger wheels in the menues.
i would just have a frend pace you at the correct speed and check it if they are off you will know it.

if it is a deal like mine it will more then likely be real close if not the same as it is now.

 

i made a small change, went from p205 75 r15 to p195 70 r15 and im off 3mph. but is cool i can at least think im going too fast LOL