WindvielBlueStang

Hi I am new to the forums and was wondering if i need a programmer.I read posts that said if you put a bigger rim without tuning the speedometer wont read right.I was wondering wats the best size i could go to without messing up my speedometer I have a 2006 V6 Pony Package which comes with the 17 inch bullits stock.I was looking at an 18-20 inch rim.Wat do u guys think.

mystang04

The rim size doesn't matter. It's the overall diameter of the wheel that affects the speedo. And even then it won't be off by that much. You don't "need" a programmer, only if you want it to be exact you can with the added benifit of more power. If you do program it you'll have to put it back to stock for warrenty work.

Stkjock

+1 on the diameter call....If all your doing is swaping out the rims/tires the dealer should be able to reflash the ECM to adjust the speedo for any change.