What do you have to do to go from 16 inch rims to 18 inch rims?

To upgrade from 16-inch to 18-inch rims, you need to ensure that the new rims are compatible with your vehicle's bolt pattern, offset, and hub size. Additionally, you'll need to select tires that fit the new rims while maintaining an appropriate overall diameter to avoid affecting speedometer accuracy and handling. It's also advisable to check for any clearance issues with brakes and suspension components. Finally, consider having a professional install the new rims and tires to ensure safety and proper fitment.