To the most technically service minded person. If anyone works for a ford garage, and knows how to recalibrate a computer on your own without having to pay the $100 shop fee, let me know. I'm wanting to upgrade my tires and rims to either 18 fx4 rims/tires or 20fx4 rims/tires. I want my speedo to be accurate, and my mileage to be true!!

Any Ideas????

 

Might help if you tell the year of the vehicle. As you are talking about 18" and 20" wheels, I can only assume you are talking 04 up, but others have made the mistake thinking they could use newer rims on the older vehicles.

 

Also, the wheel size doesn't matter. It's the height of the tire. I say this because I believe the OEM tires on the FX4's (04-07) are almost identical heights whether the wheels are the 18's or 20's.