Oh yea, if you end up getting bigger tires and/or rims you will need to get your truck's CPU flashed or reprogrammed at your local ford dealer. For example, my truck right now thinks I'm still riding on the stock 17s, it doesn't know I have 20s on it. So, my speedometer is off as well as miles till empty and the odometer reading until I get it flashed. At 35mph on speedometer I'm really going about 36.5, at 70mph on the speedometer I'm really going about 80. I have a double din unit that I can display my actual speed so I just set my cruise accordingly on the interstate. Just thought I'd mention that.

edit : just saw another member already mentioned this,
sorry.