In a large bowl, add your pimento cheese ingredients: shredded cheese, mayonnaise, cream cheese, pimentos, onion, hot sauce, garlic powder, salt, and pepper. Using a hand mixer, stand mixer, or a wooden spoon, beat until evenly combined. Taste and add more hot sauce, salt, and pepper as desired.
Spread a thin layer of pimento cheese to the edges of each flour tortilla. Roll up each tortilla and wrap in plastic wrap or wax paper. Refrigerate for 30 minutes to allow filling to firm up.
Using a serrated knife, gently slice into about 1 inch bites. Serve cold.
Prepared pimento cheese will keep for up to 2 weeks in a sealed container in the refrigerator.
To make ahead: prepare pimento cheese separately and store in the refrigerator. Assemble pinwheels the day of your event - pinwheels will get soggy after about a day in the refrigerator.