Or you can follow BlakesCakes instructions - -
Finish and decorate your cake and put each tier in a separate box. Double wrap with plastic wrap and then wrap in foil. Freeze. Travel with the boxes in coolers sitting ON TOP of dry ice. When you arrive, or the day before you need them, put the boxes in the fridge. The day of, set them on the counter and don't unwrap until they are room temperature. This way, any condensation will be on the wrapping and not the cake.
I drove 1400 miles over 23 hours with a fondant wedding cake and a bc graduation cake. After being frozen for a week and the "fun" trip, I wasn't expecting much but they both turned out perfectly.