Last month I bought a new Ford F-150 truck. It came with 17" wheels but because Ford enlarged the wheelwells for the truck bed, the 17" wheels look puny and out of place. I didn't give it much thought but my wife said it looks funny. I have found several ads listing stock Ford 20" wheels on craigslist (usually brand new and from people who are upgrading to custom wheels).
My question is do I need to get a new speedometer gear or have the dealer do anything to the computer module to compensate for the larger wheel diameter the 20" will give me?