Combine cream cheese, mayonnaise, garlic powder, and cheddar cheese in a large bowl.Use a wooden spoon to mix together evenly.
Stir in pimentos.
Place tortillas on a plate and cover with a damp paper towel. Microwave for 20 seconds. This will make them more pliable so they won't rip.
Spread 1/4 of the cream cheese mixture on each one, going to within 1/2-inch of the edges.
Arrange the ham slices on top of the cream cheese mixture.
Roll each tortilla up tightly and wrapi n plastic wrap. Refrigerate for at least 1 hour or overnight.
Cut into slices just before serving.